Without knowing you age, profession, the cost of tuition, etc. here is the best info I can provide.
In any case, if you're using federally guaranteed student loans (Stafford, etc) they don't base it on credit worthiness. The only determination they'll look at when they give you the loans is whether or not you defaulted on previous educational loans, and your income (or your parents income, if you're not an independent student) for the basis of determining whether those loans will be subsidized or unsubsidized while you're in school. Also, be sure to look into any fellowships or other stipends that the school offers to those in your program area.
In some cases, federal loans may not cover the full cost of your education. This is where private loans come in, and trust me when I say that 20-30 points will not make any difference in your interest rate, especially in an economy like the current one where consumer credit has been tightened. It still doesn't hurt to work on improving your credit score, for other reasons. We went through this process in 2003 when we were gearing up toward buying a house after a bankruptcy two years prior.
First things first - order copies of all three credit reports, as the information on each may be different. Make sure all of the information listed on them is valid (i.e. all the debts are actually yours, that your credit history hasn't been mixed up with someone else who has a similar name, etc). If there's anything there that isn't yours or accurate, challenge it by writing a letter to the creditor (cc:ing the credit reporting agency) asking that they provide evidence that the debt is valid, and if they cannot do so, demand that they remove the information pursuant to the Fair Credit Reporting Act (make sure you word it in that way). If they are able to validate it, or you see outstanding debts that are valid, make arrangements (in writing) with the creditors or collection agencies that they will report the information as "paid as agreed" or "paid in full" on that particular debt. However, don't do this for any information more than a few years old, as what this will do is re-age the debt and negatively impact your credit score rather than improve it. Bear in mind, also, that if you settle a debt, the difference between what you owed originally and what you settled it for will be reported as income to the IRS and taxed accordingly.
Try to keep open at least 3-5 consumer (revolving accounts) and one installment account (like a car, mortgage, or furniture loan), and don't ever let the balance on your revolving accounts exceed 50% of the limit (30% is preferable). No matter what, do not miss a payment. If, even after that warning, you miss a deadline, do not ever let it get to the 30-day late point, as it will be reported, and will prompt other creditors to lower your limits and raise your interest rates consequently.
Using these hints, we raised our credit score 105 points in about 6 months (from the high 500's to almost 700) and were able to get an Alt-A loan with a 5.75% fixed rate, which was pretty decent for the time we got it (2004).
Good luck. :)