When you begin your studying or homework, don't plunge right in on the new work. Spend the first two minutes thinking about what you learned last time, and about how that fits into the course outline. Eliminating most of them is easy. Eliminate some more brain interference by organizing so that you have your study tools ready in advance. Get things like this out of your head and onto paper.
Emotional interference is hardest to counteract.
Take some steps to solve your troubles and vent your angers so you can get them off your mind. Brain interference also comes when you study similar subjects one after the other. Before you turn on the memory circuits each time, check with your notes to be sure you've got the facts and ideas right. Correct misinformation and misunder- standing as soon as you know about it. The amount of attention you give a subject is as important as the amount of time you spend.