While 45 is a great round, might I suggest you look at the 9mm version as a first handgun. Less recoil, ammo costs less. You'll be shooting hundreds of rounds and costs add up quickly.
You'll need the usual gear...range bag, cleaning supplies, muffs etc. it would be best if you took a safety course first, so you know how to properly handle a potentially deadly tool. I certainly did a few stupid things for a couple weeks until I learned about trigger discipline and sweeping.