My advice is, when you are doing your classwork, do it as if you are inside the classroom - sitting down on a chair, writing your homework on top of a desk versus inside the bedroom where you might end up giving in to sleeping or in a room where there are a lot of distractions.
Create a calendar and list all the items that you need to finish on a daily manner. Set a target and achieve them.
Hope that helps!
My best advice would be to get rid of distractions and aim to have your assignments done early. Also, don't try to tackle all your schoolwork in one sitting. Take breaks every now and then to allow your mind to relax.
Good luck in your endeavors.