Start by taking a lesson and then renting a variety of things and see what works best for you. Things to consider are:
- will it serve for your purpose? Can you conceal it effectively, is the caliber of the rounds effective for defense? Is it not too big (not concealable) and not too small (bigger recoil)?
- can you shoot reasonably accurately with it? It might not be perfect… that’s what training is for… but the bullets should generally go where you want them to.
- can you operate it? Rack the slide, drop the mag, use the safety, lock the slide back, pull the trigger, clear a malfunction.
- is it manageable to shoot? You can handle the recoil, grip feels secure, weight is ok.
- is the ammo priced so you’ll be able to afford to practice? I love my .45 but its cheaper to practice with the 9mm
- is it easy to maintain? Can you take it apart to clean it?
- does it have a reputation as a reliable gun?
That’s a lot of questions, but most of that you can find out in a few lessons and a few more rental sessions.
As for where to start… we all have our favorites. I love glocks for their reliability and consistency and grip fit, and because the angle between the grip and barrel puts the sights right where I like them. Others swear by Sigs or other brands.
I like people to start by learning on a .22 so they can get some skills down before they switch to a more powerful round like a 9mm. Then they can explore what gun fits them. Some people are comfortable starting right out on the 9mm.
I think a semiauto is better for self defense, but there are reasons some choose a revolver.
Personally, I think any of the compact 9mm Glocks is a good starting point, but you’ll get lots of opinions here 