Definitely apply for childcare subsidies. Check with the financial aid office at your school for advice on where to go for them. Also, look for grants and scholarships for moms going back to school. There are a number of them and they don't have to be repaid.
Pack your own lunches. This adds up fast! You can get all kinds of ideas on lunch packing from the Bento box pictures on flickr.com. Wow, are they creative!
Once a week, do a big meal prep afternoon/evening. Soak dry beans and grains (way cheaper than buying canned/instant), chop veggies, get as much ready as possible so dinners after school are convenient for you. If dinner is easy, you're less likely to eat out for being stressed and tired, and you can take advantage of cheaper menu items like rice and beans that would require extra prep.
Get your car tuned up and keep it running optimally. Be sure the air filter and oil filters are clean. Make sure your tires are aired up appropriately. Track your mileage and see if you can improve it by adding a gas additive. Drive a little slower - it increases mileage. Get rid of anything extra in your car - you lose mpg for every 100 lb. you carry, so having extra junk in the trunk costs you money. You may be able to get school books on tape/CD from the library to listen to in the car, doing double duty while you're driving. (I did this for this semester and it was awesome! I was always up on my reading but didn't have to use the precious little post-bedtime time to do it.)
Some areas have lower electrical costs if you make below a certain amount. PG&E has one called the Care program. Check into that if your income is going to be drastically cut. You might also consider a flat monthly rate if your utility will let you, so you don't have to worry about an excessive bill.
If possible, put at least $1000 into an emergency fund, and the amount of any insurance deductibles, while you still have extra income. Having that little cushion is great for peace of mind, and if you have a car accident you're not SOL putting everything on credit.
Good luck! I went back to school this semester and it's been exhausting but so rewarding. Only 3 more years to go!
