Handgun Sights
At a bare minimum you NEED a tritium dot in your front sight. Ever since the handgun was invented people have been trying various methods to make the front sight easier to see, especially in low light.
In the old days guys used to paint their front sight a loud color to help it stand out. Somewhere along the line somebody thought of putting a small gold insert in the front sight and buffing it to a high shine so that it would be more visible in low light.
Today practically every maker out there offers a weapon with tritium sights pre-installed from the factory. While this is a good thing, unfortunately the dominant sight configuration is to have three "dots", each with a tritium vial in it that is the same size, color, and brightness. This, as it turns out, isn't an ideal setup.
When you look through the sights of a handgun, the rear sight appears to be bigger than the front sight of the handgun. This is because it is closer to your face.
In low light with tritium sights that are all the same color and brightness when side by side, the rear sights are actually going to appear to be bigger and BRIGHTER than the front sight, making it harder to find and focus on the front sight under stress.
Thankfully there are sight makers who have realized this and who offer sights in various color combinations to try and help a shooter to distinguish between the front and rear sights under stress.

This picture of a typical 3 dot night sight setup, generously provided by a member ofM4Carbine.net, illustrates my point.
While this is progress, it still isn't ideal.
Even with orange or yellow rear sight "dots" you can still end up losing the smaller, dimmer front sight.
As a result I've pretty much transitioned all my carry guns to a plain black rear sight and a tritium front like the plain black Warren Tactical rear sight you see here on my M&P.
With this arrangement I have found that even when shooting in almost no light I can make A zone hits without problem using just my glowing front sight out to 25 yards.
A plain black rear sight is useable and more accurate than a traditional three dot setup under stress, but still isn't ideal.
Some folks have examined the problem and have come up with a great solution: Make the rear sight "dots" smaller and dimmer. Scott Warren is one of those folks and he created a rear sight with a smaller subdued dot and a front sight with a green dot of standard size and brightness, and the result is the best night sight setup I've tried.

You can see the Warren rear sight with smaller, subdued tritium elementon my Glock 19 here.
The rear dot doesn't distract from the brighter front dot but it does allow you to figure out where your front sight is in relation to the rear sight… and at least in my experience the vertical dot-on-dot arrangement seems to align very naturally for me.
I currently run the Warren 2 dot sight arrangement on all of my Glocks and M&P's.

Plain black Warren rear.
The following pictures attempt to illustrate some of the differences in sighting setups. They are fuzzy because the camera wasn't at all happy with the level of light being used, and the fact that I was trying to snap the picture with one hand while holding the weapon with the other didn't help any either. Still, while they aren't 100% true to life, they do help illustrate the point.

First up, plain black sights as found on a S&W K frame.

Next, the plain black rear with a tritium front.

Next, the Warren tritium rear with tritium front.
I know what you're thinking... where are the 3 dot sight pictures?
Well I couldn't get the camera to take a useful picture of the 3 dot setup.
Handgun Lasers
The best available option for low light shooting with handguns these days is the laser. While lasers aren't as durable or reliable as iron sights with tritium vials in them, they are MUCH easier to use in low light than even iron sights that glow.
Our natural instinct when we perceive a threat is to focus intensely on the threat itself… and yet to be accurate with a handgun you have to focus on some sort of sighting reference (like the sights) rather than the threat.
The laser, on the other hand, allows someone to see a valid aiming index that is literally ON the target, working more in line with how we operate under stress. The laser is to the handgun what the red dot is to the carbine, a simpler aiming index that allows for more accurately placed fire under stress and especially in low light.
I know that some people have regarded lasers on handguns as unnecessary "gadgets" and something that shouldn't be used for any serious purpose. Many of those people have changed their tune and now heartily recommend lasers to their students.
Lasers are really something that you can't fully appreciate until you've given them a shot. Explanations invariably fail to communicate the true benefit they offer. The best example is the little S&W J frame.

The J frame is probably the single most difficult handgun to master.
It's got a heavy trigger, a short sight radius and stock sights that are almost impossible to see even in bright daylight.
With a laser attached, however, it suddenly becomes easier to get a good sighting index.
Ask anyone who has used the CT grips on a revolver for serious evaluation and they'll tell you that they have used them to make shots they never could have made without the laser. My own personal testimony is that I and several other shooters were able to use a S&W J frame at about 15yards in almost pitch blackness to make solid center mass hits on a target with the laser activated. Everyone who tried it was sold on the utility of the CT lasers.

As an example, this is what it's like to try and aim the J frame in dimming light.

This is what it looks like when you use the laser.
It takes some dedicated training and practice to learn to use the laser properly, but it's worth it.
They are also tremendous training tools. The laser offers you instant feedback on your trigger control.
If you see the laser making a checkmark or a U while you shoot, you are snatching the trigger.
It's much more difficult to get that kind of feedback from iron sights.
At a bare minimum you NEED a tritium dot in your front sight. Ever since the handgun was invented people have been trying various methods to make the front sight easier to see, especially in low light.
In the old days guys used to paint their front sight a loud color to help it stand out. Somewhere along the line somebody thought of putting a small gold insert in the front sight and buffing it to a high shine so that it would be more visible in low light.
Today practically every maker out there offers a weapon with tritium sights pre-installed from the factory. While this is a good thing, unfortunately the dominant sight configuration is to have three "dots", each with a tritium vial in it that is the same size, color, and brightness. This, as it turns out, isn't an ideal setup.
When you look through the sights of a handgun, the rear sight appears to be bigger than the front sight of the handgun. This is because it is closer to your face.
In low light with tritium sights that are all the same color and brightness when side by side, the rear sights are actually going to appear to be bigger and BRIGHTER than the front sight, making it harder to find and focus on the front sight under stress.
Thankfully there are sight makers who have realized this and who offer sights in various color combinations to try and help a shooter to distinguish between the front and rear sights under stress.

This picture of a typical 3 dot night sight setup, generously provided by a member ofM4Carbine.net, illustrates my point.
While this is progress, it still isn't ideal.
Even with orange or yellow rear sight "dots" you can still end up losing the smaller, dimmer front sight.
As a result I've pretty much transitioned all my carry guns to a plain black rear sight and a tritium front like the plain black Warren Tactical rear sight you see here on my M&P.
With this arrangement I have found that even when shooting in almost no light I can make A zone hits without problem using just my glowing front sight out to 25 yards.
A plain black rear sight is useable and more accurate than a traditional three dot setup under stress, but still isn't ideal.
Some folks have examined the problem and have come up with a great solution: Make the rear sight "dots" smaller and dimmer. Scott Warren is one of those folks and he created a rear sight with a smaller subdued dot and a front sight with a green dot of standard size and brightness, and the result is the best night sight setup I've tried.

You can see the Warren rear sight with smaller, subdued tritium elementon my Glock 19 here.
The rear dot doesn't distract from the brighter front dot but it does allow you to figure out where your front sight is in relation to the rear sight… and at least in my experience the vertical dot-on-dot arrangement seems to align very naturally for me.
I currently run the Warren 2 dot sight arrangement on all of my Glocks and M&P's.

Plain black Warren rear.
The following pictures attempt to illustrate some of the differences in sighting setups. They are fuzzy because the camera wasn't at all happy with the level of light being used, and the fact that I was trying to snap the picture with one hand while holding the weapon with the other didn't help any either. Still, while they aren't 100% true to life, they do help illustrate the point.

First up, plain black sights as found on a S&W K frame.

Next, the plain black rear with a tritium front.

Next, the Warren tritium rear with tritium front.
I know what you're thinking... where are the 3 dot sight pictures?
Well I couldn't get the camera to take a useful picture of the 3 dot setup.
Handgun Lasers
The best available option for low light shooting with handguns these days is the laser. While lasers aren't as durable or reliable as iron sights with tritium vials in them, they are MUCH easier to use in low light than even iron sights that glow.
Our natural instinct when we perceive a threat is to focus intensely on the threat itself… and yet to be accurate with a handgun you have to focus on some sort of sighting reference (like the sights) rather than the threat.
The laser, on the other hand, allows someone to see a valid aiming index that is literally ON the target, working more in line with how we operate under stress. The laser is to the handgun what the red dot is to the carbine, a simpler aiming index that allows for more accurately placed fire under stress and especially in low light.
I know that some people have regarded lasers on handguns as unnecessary "gadgets" and something that shouldn't be used for any serious purpose. Many of those people have changed their tune and now heartily recommend lasers to their students.
Lasers are really something that you can't fully appreciate until you've given them a shot. Explanations invariably fail to communicate the true benefit they offer. The best example is the little S&W J frame.

The J frame is probably the single most difficult handgun to master.
It's got a heavy trigger, a short sight radius and stock sights that are almost impossible to see even in bright daylight.
With a laser attached, however, it suddenly becomes easier to get a good sighting index.
Ask anyone who has used the CT grips on a revolver for serious evaluation and they'll tell you that they have used them to make shots they never could have made without the laser. My own personal testimony is that I and several other shooters were able to use a S&W J frame at about 15yards in almost pitch blackness to make solid center mass hits on a target with the laser activated. Everyone who tried it was sold on the utility of the CT lasers.

As an example, this is what it's like to try and aim the J frame in dimming light.

This is what it looks like when you use the laser.
It takes some dedicated training and practice to learn to use the laser properly, but it's worth it.
They are also tremendous training tools. The laser offers you instant feedback on your trigger control.
If you see the laser making a checkmark or a U while you shoot, you are snatching the trigger.
It's much more difficult to get that kind of feedback from iron sights.