Keep your peripherals tucked away in your bag. Make sure your battery is fully charged before you get to class. Carry an extra battery just in case. Know how to use your computer before you get to class. Keep a pen and paper handy just in case your computer doesn't cooperate.
Accessories Get one with a specially designed backpack or shoulder harness bag.
One that's big enough to hold a notebook and some pens, just in case. Strong, padded straps will keep your hands free and your shoulders cushioned. Have a lot of pockets for floppy disks, zip disks, printer cables and anything else you plan on using. Get a waterproof case, you never know when it's going to rain or you may spill coffee on it. Get a lock for it.