If it's prose, I write one or more essay(s) on the topic after reading the topic and mulling over it for 1 or 2 days. Oh - and this one makes me look crazy but

If it's prose, I write one or more essay(s) on the topic after reading the topic and mulling over it for 1 or 2 days. Oh - and this one makes me look crazy but here goes nothing - I teach it....to myself that is, in my own mind that is, usually while exercising! How weird is that! I become these 2 persons in my head - 1 is the teacher, 1 is the student - and I pretend that teacher-me is teaching the subject to student-me, using own vocabulary. Sounds weird, but it works for me. If it's programming, I implement the concepts I read. If it's math, I write notes, solve related problems and try to come up with related corollaries. In general, using whatever I've read in some way seems to help me a lot.