Welcome! Devrij's advice is good listen to it. I started as a newbie aswell and didn't rush into things. Did my research read reviews, forums etc. I suggest buying things in this order.
Mask [ JT FLex, Grills, Events, Proto Axis ]
No fogging, Enhanced Gameplay, You will perform much better, Greater vision etc.
Pack [ Nxe ]
Cheap pack makes a big difference. Easier to reload and haul paint around rather than a crappy rental one which is falling to bits.
Pants [ Dye, Proto, Eclipse, Angel etc]
Comfort, Easier to run, Bounces etc.
Gloves [ Any ]
Stop your hands getting ripped to shreds and better grip on marker.
Marker & Hopper [ Any]
Obvious reasons, reliability, accuracy, range, bps etc etc.
Carbon Air Tank [ Any you fancy ]
Lighter, More reliable and more shots per fill.
Other Essentials/Choices: Headwear, pads, footwear, Jersey, squeeqes, pods, Towel, Caddy etc.