you need a 9mm
seriously, unless you are made of money, you will find that practicing and shooting competitions with a 45 cost prohibitive. You can do it, but you'd get a lot more of it done with a 9mn, or even a 40. If you're intent on sticking with a 1911 style gun, then 9 or 40 will work great for you.
If however, you really want to stick with the 45, what you will need, regardless, is: A good quality holster, you can go full on race mode and get a Double Alpha, Alpha X holster or you can get a kydex holster like their PDR Pro II, there are a ton of other manufacturers for all the gear, CR Speed, Ghost, Black Scorpion and so on. You will absolutely need a good belt, again from DAA, CR, Ghost and so on. Mag pouches, if you stick with the 45 you will want at least 5 of them, again, all the manufacturers I listed make great pouches. A couple magnets on those pouches is also a good idea. Beyond that, good cleaning gear and solutions, I use ProShot Products for all that, but again, there are a ton of different ones. Stay away from CLPs, they suck, Clean, Lubricate, Protect, also known as Jack of all trades, Master of none. Ear and eye protection you probably already have.