I would say just take what you have to your first match. Shoot it. Then see what you feel like you need to buy.
I don't know how many times I purchased some piece of gear, used it once, and thought to myself "why the heck did I do that?" Just shoot and have fun, after a while you will figure out what your style is, then you can spend your money.
The only thing that is probably really going to help right at the start is an extension for your shotgun.