Check out the action, see how smooth or how difficult it is to rack the slide.
If there is a hammer you can check the trigger pull without letting it dry fire onto the firing pin. Some of them have internal hammers so you can't check the trigger without dry firing.
See how it fits your hand. See how big or small it is.
Some of the things you may not like about the handgun can be worked out by a gunsmith, different hand grips etc... But you may as well start off with something that you really like and then further customize it later, if you need to/want to.
After saying all that, what I usually do is purchase the handgun for my particular need (concealment or hunting protection) and then learn to shoot the handgun afterwards. Find out the way it shoots with my shooting style and how best I can use it.