Zolgar: Step one, find someone who has a gun. Glock 17 or .44 Magnum are two very good choices, break in to their house while they are at work (for this you need a brick, or large rock), steal their gun. Take a few other valuables too.
Make sure you wear gloves and tie your hair back carefully. Leave someone else's hair at the scene, maybe some school bullies or something. that'll get the heat off of you.
Go to a Circle K or 7-Eleven, do NOT hit an indy store, watch and see if your local Circle K's have security guard, too. Scope out a good store and a good time.
Get yourself some shoes that add 6 inches to a foot of height, and one of those fake-hair hats in a different color. Dark sunglasses, too. Come back at that good time, check and make sure you're clear, you gotta be careful here anyone around could really ruin your day. Pull your gun and demand the register be emptied.
The clerk WILL hit the silent alarm, so be ready to flee, and fast. But they should give you the money, if they stall too long, book it anyways.
Remember that persons hair you left at the prior house, leave more at the store.
Then you just need to enjoy the .. $87 that you got, and risked going to juvie for. :)

Gexecuter: So anyway if any of you guys are poor like me there's a way to earn cash, both involve online surveys. It's how i have been able to buy GOG games even tough i don't have access to a credit card or the ability to add funds into my paypal account trought bank transactions. Tough I dunno if it's allright for me to talk about my method here, if we would have some sort of PM feature it would be easier that way.