It is important for you to have a "homework routine"established. Once you have relaxed a bit and are ready to tackle the responsibilities of being a student, don't procrastinate, just do it!
STEP 1: Start with your shortest tasks first and then take a 10-15 minute break when done.
STEP 2: Start working on your harder assignments. Set yourself a timer and work for 30 minutes straight with no distractions.
STEP 3: Take a 10 minute break when the time is up and to do whatever you want.
STEP 4: Repeat steps 2 and 3 until done.
A good way of creating this habit is to have a designated area in the house used only for completing school work. It can be the living room, the kitchen table, your room, the porch, or any "quiet" place. The point is to be focused and ready to complete your homework.
During break time move away from this area so that your brain starts associating work with your homework area.