As others have said, the best thing you can do to start is to take NRA Basic Pistol, and then rent as many different makes and models as possible. That said, it can still get overwhelming; in many ways, we are living in a golden age, as there is an insane variety of good, reliable, and accurate guns on the market at reasonable prices. That's great for us enthusiasts, but it also lead to paralysis by analysis as you try to figure out where to even get started.
1. First, and most important, how much are you willing to spend on your gun this year? Keep in mind that there are a lot of secondary expenses that come with owning a gun. Ammo is the big one, but there's also cleaning supplies, a safe, spare magazines, eye and ear protection, range membership/targets, etc. It adds up really quickly.
2. What state do you live in? What are the restrictions on gun ownership where you live?
3. Do you plan to get a concealed carry permit? Or will you mostly be keeping the gun at home for home defense and target shooting?
That will help us narrow your search parameters a bit. Now for important things to consider when trying guns:
4. You want a gun that fits your hand well. A comfortable gun will be both more accurate, and more fun to shoot. A gun you ennoy shooting is a gun that you will lractice with.
5. You want to be able to confortably reach all the controls. If it has a safety, make sure you can easily and smothly flick it on and off without breaking your grip; if it's double-action (revolver or auto), you have to be able to reach the trigger in double action mode without breaking the grip. If you can't, that's an absolute dealbreaker. It's not so essential to be able to reach the magazine and slide releases one-handed, but it's always a nice bonus when you can.