Sam you did an outstanding job on ur second point. The only way I know to get better is just do a lot more of it. This skill does not give itself up easy. You will have to put in the time to earn it. That being said, you got an eye for it and should be fine.
Thinning takes technique and pressure in the right spot/direction. If your flakes are stopping at center it might be caused by any number of things from poor setup, improper holding, not enough pressure (ishi stick can help with that,) or you just weren't holding ur tongue right. When you begin to develop the feel for it, it's gonna feel a little like magic at first. And don't get depressed when you bust the next 20! It's just a rock until it's a point.
Scott