I only have one semi that is not laser equipped, and I will be installing one on that handgun shortly. A use perspective;
-completely familiarize yourself with your chosen weapon pre-laser installation, put mutiple box's of ammo through it on target.
-after installing the laser take the time to dial it in. This will require a rest and pad with careful vertical and horizontal adjustments between rounds until the hard sights and laser are perfectly aligned and rounds are hitting center target.
-regarding laser choice, green lasers are easier to see and pick up than red lasers, and are also 2x expensive, so I make do with red.
-once lasers are dialed in whatever that dot paints is where the bullet should hit. So in a crisis situation, a laser equipped handgun can be fired accurately prior to the hard sights being lined up on target, and that may be the most important attribute of laser equipped handguns.
-I practice drawing and firing with both hard sights and with laser dot only, firing as soon at the target is painted and it is always quicker.