Some of this is from experience and some from necessity:

- If you're riding in the dark, make sure you can be seen and that you can see where you're going. Day-Glo safety vests are dirt cheap.

- Get reliable tires and learn how to change a flat BEFORE you get a flat OR make sure your cell phone is fully charged so you can be picked up.

- Target and WalMart carry all sorts of cheap non-bike specific workout clothing that will get you by until you can afford the overpriced stuff everyone else uses.

- Make sure the bike is tuned up so that it shifts and stops like it should.

- http://www.cyclistview.com/