Have trouble finishing your homework because you can't concentrate or you just really don't feel like it?

Here's the guide for you.

[edit] Steps

Go to the room in your house, dorm, apartment, or whatever you have that you feel most comfortable and focused in. Turn on the music that makes you feel better even on a very bad day. Don't put the music on headphones.
Be seated comfortably in a place not near a TV or computer if you can. Don't sit like they always tell you with your back straight and feet flat on the floor. Sit how you want to sit. Just don't lay down.
Take out your homework and figure out which homework is due soonest, which homework is hardest, and which homework you can finish during your school day if you must. Stack the paper or books in a pile from earliest that can't be done in school to homework that isn't due earliest or that can be done in school.
Place your work in front of you and the book (if there is one) behind that, close enough so you can easily read.
Start your homework. When finished, reward yourself by watching your favorite show on TV or the Internet or going to your favorite restaurant or whatever else you can think of.
Maybe try going to the library after school. Chances are that the librarian can help you with any questions you have and it is much easier to get focused in such a quiet study oriented area like the library.

[edit] Tips

Your homework may take several hours to complete. You must take a break at least every 50 minutes. If you don't your brain will wear out, you will get bored.
Work at a slower rate. Try finishing one subject of homework, getting a snack, and then moving on to the next one.
Try chewing gum that has a flavor you like but not too sweet.
If you have homework that isn't due for a week and you have extra time, do at least a part of it before you reward yourself.
Don't just jot down things on your homework and assume your teacher won't notice, take your time and relax.
Reward yourself, e.g. ice cream, a cookie, checking your email, etc. But not too many unhealthy foods!
Keeping a water bottle nearby and refilling it often keeps your head clear and can be EXTREMELY beneficial.
If you have tests to study for, try reviewing AFTER the actual work is done. Remember that you can always review for tests in the morning while eating breakfast, on the bus or car ride to school, and right before class starts. You don't necessarily have to cram all of your studying into one session. In fact, many people have found that spreading out studying time helps them recall information better.

Do not lay down. Don't tell yourself "Just five minutes then I'll get back to my work." Most people will fall asleep during those five minutes.
Don't rest your head. Again you will fall asleep.
Don't listen to music that you know the words to because you will end up singing the song in your head and will lose focus on what your reading or writing.
Don't study with a friend or you will get sidetracked.