Hi Miranda,
Respirator is the most important piece of kit to start with... always make sure it is a good one... and plenty of ventalation where you are spraying. You'll need some glossy poster board, display board, your local art shop should be able to supply you, but do shop around, it can get expensive when you are just staring out.
Some bright bold colours, i buy mostly primary colours, red, blue, green, yellow, white and clear coat, try and buy cheaper black you will use a lot for planet paintings, some pallet knives, you'll probably get attached to one and that will be your favourite. Hi gloss magazines for texture creating, sponge brushes, small towels (flanels, we call them here in england), some sea sponge (good for creating leaves).
Also experiment as much as you can. Watch the tutorial videos here, and you tube... lots out there... you'll make lots of mistakes, but try and bring the painting back, some of my best work is created from mistakes...
Happy spraying! Hope to see some of your work soon! GOOD LUCK!
SPRAY SAFE!