Financial preparation & advice before Graduate School?

Try to get a teaching or research istantship with whatever program you enter - holding down a job while in grad school is hard to do; some programs actually make you sign a form saying you won't have a job outside the program because it takes time away from your coursework and research and your grades will suffer as a result. Grad school is more than a full time job on its own. TA or RA positions give you some flexibility about when you work, so you can still get your homework done. They don't pay a lot, but usually it pays the rent and you're not taking out more loans - they also pay your tuition.