What seemed to work for me:
1. I started reading very early in life, and like early sports and music learning, I think this made a difference.
2. Most recall and understanding is relative to existing knowledge, so the more you have to link up to (and the more you read with linking up in mind) the better.
3. I've found that association (2.) works better than trying to understand everything while reading (the understanding is generally there the next day).