I always heard that you have to go over something 6 times until it becomes stored in long-term memory. I usually take notes during a lecture, that evening I will transcribe them into a better format (in pen), filling in everything in a little more detail. The next day I will simple read them over highlighting the things I could not immediately remember. After that I will review only the highlighted material. Then I will re-review everything and type the notes up clear, compact, and concise. Before any major test I just scan over the notes, and I usually know everything, thus feel more confident on the tests.
That way I go over it at least 6 times before it's needed.
I don't do this for everything though. If it is a subject I am really interested in I won't start this method until I get stuck on something. It helped out a great deal in some of my humanaties courses where I was required to remember names/places/ideas/movements/artists that I really had no interest in.