I did the same thing until I watched Saw Filer for a few days and asked lots of simple, dumb questions. Questioned about every thing he did, why he was grinding this way, why he was taking this flake instead of that one...I wouldnt say I learned how to, but I did get to see him put "english" on a flake. That was interesting...and I only thought flakes went the direction pressure was applied directly.
Hardest thing for me to get was not just taking flakes of opportunity, but making sure I had a good edge to work with and making sure my edge (platform) was close to the surface I wanted to take the flake from. Hard to take a long flake from a steep platform and hard to take one from a surface that has concavities on it.