Now when I am learning something I always try to explain it in my mind (or write it down) to imaginary 'student'. It's so effective it's amazing. It lets me catch many knowledge 'holes' in my new studied topic. Whereas I used to just read the material (multiple times) and imagine that I know it. If somebody does not know what I am talking about just try to explain some topic you recently.
P.S. AFAIK, teaching is the best way to study/learn new topics.