Sounds like the right gun for you is probably an M16 to start off with and then slowly convert it to a SPR or SAM-R. It's not like converting it will instantly make your gun more accurate though, it will just look like it on the outside.
Don't worry about rentals, rentals can usually be found beforehand by letting people know you're a new player and need to rent some stuff then you can do rentals privately between you and another player.
As for the gear you should have. It's not necessary to have military boots but they are good. At least have hiking boots (perferably in an "earthy tone" so as to stick out too much) that give good ankle support. Paintball mask/goggles if you have one but most fields can rent those out. If you have BDU's then that's great but if you don't, a full set of OG107/Olive Drab can be found at most surplus stores for less than $50 usually (used of course). Also ask for a chestrig and mags too or midcap mags that carry ~120 rounds in them and storing them in your BDU pockets.
You're good to go then. Trying it out by renting means also that if you decide airsoft isn't for you you're only down rental fee, gas money, and field fee whereas if you bought a gun outright you'd be down the deprecation value, gas money, and field fee. As for major purchases the best deals are in the classifieds. So Age Verification is your best option and can be done at the field if there is an AV rep attending (just ask if there will be an AV rep attending who can AV you).
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE