E-mail your instructors and ask what textbooks they're planning to use. I have done this every semester so I can purchase my books from places like half.com and Amazon. Also, bigwords.com is an excellent site for finding the best prices on textbooks.
If you're taking and English or literature classes, sometimes you can get away without buying the book... many of the texts can be found online. Discuss it with your instructor first.
Also, see if your school's Associated Students Council offers any book grants or loans... some will do this, some can't. It all depends on what's in their budget. It's worth asking!
As for school supplies, check the sale ads. It seems like everyone has stuff for 10 cents. Bring the ads and all the kids into WalMart and do a price match so that you don't have to drive all over the place. If you have a Rite Aid near you, there's some coupons that combined with the sales makes free school supplies. (This week there's free Mead notebooks, free glue, and free crayons.) If your Rite Aid no longer has the tearpads, PM me with your address and I'll send you some coupons. They were a big sheet of paper, about the size of notebook paper. (Unless the mailman is unusually slow, you should get them Saturday if I mail them today. Just let me know how many coupons you'd need.)
As for soap, toothpaste, etc, check out CVS's and Rite Aid's Extra Care Bucks and rebate programs if you don't do those already. I get tons of free stuff (even paid to take stuff after coupons) from both places. Rite Aid has Dawn dish soap on sale for 99c this week, and with the $1/2 coupon from the paper a few weeks ago, it makes them 50c each. Hotcouponworld.com, afullcup.com, and slickdeals.net have tons and tons of threads about those.