My 2 cents...
1. Order Brian's book or use the online version in this web site (and read all of it - even the parts of crystal you think you are good at).
2. Use the built in crystal help.
3. Create some sandbox reports and Read as many posts as you can on this site and try to replicate both the problem and the solution. It is a great way to increase your skill level, get you out of a comfort zone and learn different approaches from different posters.