It's trial and error. You have to experiment until you find what works best for you. There isn't a forward or reverse pitch or lateral pitch that is "the best", only "the best" for YOU. If your thumb is exiting clean, and not hanging or getting ripped up..you're probably good. If you're thumb is irritated on the inside, you have to add lateral under, if it's tearing skin on the outside you need to add left lateral.I have right lateral (under) and forward pitch in my thumb and it's great. I know many other bowler's that this would not work for. They would hang everytime.
