how to organize a school locker well for the whole school year?

If your lockers are big enough, get a locker shelf. That way, you can stack and organize your binders/textbooks in whatever way you want.

If your locker is too small, then don't worry. I usually keep my jacket on the hooks of my locker, and I keep my binders all in a straight line. I tend to have a lot of papers/water bottles in my locker, and it gets really annoying.

If you have any papers that you know you don't need, don't stuff them into your locker, just throw them out into the garbage. If you find that you have a lot of papers in your locker, clean out your locker. Make sure you check the papers beforehand, so you know what you're throwing out is to use to you or not. Also, don't keep any food or juice in your locker for longer than two days. You can have bugs come into your locker, and it will probably start to smell.

Have monthly clean out of your locker, on a set day. That way, you know when you will clean out your locker, and it will probably stay cleaner for longer.

If you're a guy, ....eh...you probably shouldn't. It just seems unnatural for a boy to do it. Just be sure to avoid carelessly throwing your stuff in there. Clean it out each week so it doesn't turn into a disaster.

IF you're female or want it anyways (hey, who cares what others think?) Here's some cheap organization things - locker shelves and pencil cups (magnetic) - http://www.organizeit.com/locker-organizers.asp