This is a topic that comes up frequently in family sessions.  Here is a guide found on http://www.add.org/teenhomework.html.  This one is specifically for teens with ADHD, however, many of the pointers are helpful with any teen.
 
Analyze with your adolescent the points at which there is a breakdown in homework skills.
  • Does your adolescent record the assignments in an assignment book, sheet, planner, or in some other organized manner?
  • Does your adolescent bring home from school the assignment books, textbooks, notebooks, and other materials needed to complete homework?
  • Do you review the assignment book and also have an independent means of ensuring that your adolescent is accurately recording the assignments?
  • Does your adolescent select a quiet, non-distracting, well-lit, and comfortable place in which to do the homework?
  • Do you help your teenager develop an organized plan of attack to sequence multiple homework assignments and study in one evening?
  • Have you and your adolescent agreed upon a starting time for doing homework, and does your adolescent adhere to this agreement?
  • Are you or another responsible adult present in the house to “keep your teenager honest” when you expect him/her to be completing homework?
  • Is your adolescent able to sustain his/her attention long enough to complete the homework? Have breaks been built into the plan?
  • Do you review completed written assignments and quiz your adolescent on material studied for examinations?
  • If your adolescent takes stimulant medication, is there an adequate homework dose “on board” during the designated time?
  • Do you coach your adolescent to use a calendar to track long-term assignments and periodically work on them instead of leaving them for the last minute?
  • Does your adolescent have a plan to make sure that the completed assignments actually get to school and are handed in on time?
  • Are there incentives to motivate your adolescent to do homework?

Develop a comprehensive homework plan which addresses those skill weaknesses which you have identified. Write this plan down as a behavioral contract to be signed by you and your adolescent. Below is an example of such a plan. This plan addresses all the components of the homework process identified above. Your plan may only need to address those components which apply to your adolescent.

Robert’s Homework Plan

I, Robert Jones, together with my parents, agree to carry out to the best of our ability the following homework plan:

I. Keeping Track of Assignments

A. I will write down the assignment from the board every day before I leave each class. I will write the assignments in the section of my school planner for that day and subject. I will read over what I have written down to make sure I understand it.
B. I will ask the teachers to explain any assignment which I do not understand. I will get the phone number of a friend in each class, in case I need to call them to check on the assignment. I will write their names and phone numbers in the front of my student planner.

II. Bringing Home Materials

A. During lunch time or a free period, I will review my assignment sheet and gather all the materials which I need to bring home to complete my homework. I will put all these materials in my backpack.
B. As I leave my last period class, I will think to myself, “Do I have everything I need to do my homework?” I will remind myself to check for materials by setting the alarm on my watch to go off at the end of the school day.

III. Reviewing Assignments

A. I agree to show my mother my planner every day without a hassle so she can review the assignments. My mother agrees not to nag me about seeing my assignment book, only to ask one time. Over time as I demonstrate responsibility in accurately recording my assignments, my mother agrees to ask to review my assignment book less often.
B. My mother agrees to talk to my teachers and arrange to obtain a list of the week’s assignments in advance as a way of checking the accuracy of my planner.

IV. Establishing an Appropriate Setting and Schedule for Homework

A. From Sunday through Thursday, I agree to work on homework from 6:00 p.m. to 8:00 p.m. If I finish early, I will show my completed work to a parent, and if they agree that it is completed, I can do whatever I want. Each Friday, I will discuss with my parents a specific time to do homework over the weekend.
B. I will do my homework at the big desk in the den. I can listen to soft music with headphones, but no loud rock, television, or computer games.
C. My mother will remind me once without nagging to start on my homework at 6:00 p.m. I will start without an “attitude.”
My mother agrees that she will be present in the house during homework time, and that she will occasionally cruise by the den to see that I am doing my homework. She agrees not to “hover” over me.
V. Medication
I agree to take a dose of my prescribed stimulant medication at 4:00 p.m. on Sunday through Thursday, to help me concentrate on homework. On the weekend, I agree to take my medication one hour before I start my homework.

VI. Daily Plan For Organizing Homework Completion

A. I will make an organized plan for attacking each night’s homework. This plan will guide me in what I subject I will do first, second, etc. It will also divide up homework time between assignments due tomorrow and long-term assignments. I will tell my mother the plan without an “attitude.”
B. My plan will estimate the time needed to complete each assignment, as well as how I will check each assignment over for accuracy, completeness, and legibility.
C. The plan will include time for studying for examinations, and whether I am going to work a little bit on one of my long-term assignments.
D. The plan will specify how often I will take breaks during homework time, how long the breaks will be, and how large assignments will be divided into smaller units.

VI. Reviewing and Correcting Assignments
1.    I agree to show my completed written work to my mother.
2.    My mother agrees to check over my work for completeness and accuracy.
3.    I agree to make the corrections which my mother suggests.
VII. Turning In Assignments
1.    As soon as I finish an assignment, I will put it in the section of my binder for that class. At the end of homework time, I will put my binders and books in my backpack.
2.    I will do my best to remember to hand in each assignment.
3.    My mother agrees to talk to my teachers to make sure the teachers are clearly prompting me to turn in my homework.
VIII. Incentives

My parents agree to let me choose one of the following privileges each night that go along with everything in this homework contract:

1.    20 minutes of long distance phone calls.
2.    One credit toward renting a video. If I get four credits by the weekend, I can rent a video.
3.    30 minutes of Internet time.
4.    Credit toward a 30-minute extension on my weekend curfew. If I get five credits by the weekend, I will have an extension of 30 minutes on my Friday and Saturday curfews.

Implement the Contract for Several Weeks and Then Revise It as Necessary. If you are running into power struggles, a great deal of defiance, or resistance from your adolescent, consult a psychologist or other mental health professional for assistance.

Below are several books with excellent suggestions for helping adolescents with ADHD complete homework more effectively:
1. Markel, G. & Greenbaum, H. (1996). Performance breakthroughs for adolescents with learning disabilities or ADD. Champaign , Illinois : Research Press.

2. Robin, A. L. (1998). ADHD in adolescents: Diagnosis and Treatment. New York : Guilford Press.
3. Zentall, S. S. & Goldstein, S. (1999). Seven steps to homework success. Plantation , Florida : Specialty Press