Well there's a lot of leeway here and a lot of adjustments you can make based on where you live and what kind of tradeoffs you're willing to make. Here are some good budgeting rules of thumb.
Your rent/mortgage should be about 25% of your monthly income after taxes. That's a great rule of thumb. If you live in LA or NY then you're going to spend more of your monthly income on rent. Don't spend more than like a third of it though, that's retarded.
Your student loans should be locked in unless you refinance. If you refinance you'll pay longer, the total amount will be higher, but your monthly payment will be less. Considering the fact that your loans will be forgiven no matter what the balance is after 20 years, under this new legislation, i'd just take whatever the locked in rates are. (i'm also assuming you have just stafford and perkins loans to pay, not any private ones.)
You should be saving about 10% of what you earn, too. This is above and beyond a 401K contribution. You need to have a safety net fund of about 6 months after tax income, in case something horrible happens.
Car insurance. Get the cheapest plan you can get. I'd say 100/300 is a good solid safe coverage. If you have a newer vehicle, I'd get comprehensive collision on it too. I'd get some deductable you could pay in one pay check and still cover your mortgage, utilities, loans and food for the week (so basically if you crash your car, you can pay for it in one paycheck, but you won't be having any fun that week)
You're going to spend money on food. You're going to spend a lot, and that's okay because you need food. Spend it wisely though. Go to the grocery store, get stuff that's on sale. If you're spending more than 33% of your after tax income on food, you're being stupid (or your fat).
Health insurance. I hope you get it where you work if you've got a masters. If you're self employed this is a whole new ball of wax. Spend as little as you can on your policy. High deductable, with a corresponding HSA is the most cost effective way to go.
Also, use your credit card for what it's for. It's not for buying things you can't afford, it's for paying for stuff between pay periods. If you get paid 2000 bucks a pay period lets say, and you run an 1800 dollar credit car balance for those two weeks, and then pay it off with your check, that's fine.
Don't run a balance though, that's retarded. Credit card debt is for people who don't make money. You're in grad school, you're going to make money. Spend it like a smart person!
All the best. I hope the real world turns out well for you.