Before beginning your homework make a to-do list. For example your homework is the following: write a poem, read a history chapter, solve 20 math problems. Then, number the tasks, from toughest to easiest, and start with the hard stuff. The "save the easiest for last" strateg will help you finish on a high note. (Maybe inspire you to get in some extra studying.)
Consider different time slots you can use to get work done. For instance, maybe you could set aside a weekend morning or Sunday night. If time during the school day, some teachers give time to complete homework and other assignments. Take advantage of your teacher's kindness and you won't have as much homework.
Homework is a chance to prove your independence to yourself, your parents, and your teachers. You are showing your independence when you start and complete your homework on time and doing it by yourself. Though if you need help, please ask a parent, teacher, counselor, or staff member at school.