There's not a short answer here. First of all, you have to know the shot, and knowing the shot comes from paying a lot of attention to the ball reaction you get in practice. If it's at league and it's always the same shot, you should already have a good idea. You have to watch your ball reaction closely so that you can create your own mental lane graph. Then you also have to watch everyone else that's bowling and where they're playing at, that might be what's tripping you up. If you go to move, but move right into someone else's track burn or carrydown, if you haven't been paying attention, that's most likely going to be confusing.
Does everyone NEED to or want to pay that much attention, probably not. It just makes me feel lazy or oblivious if I don't. Even on my worst nights this year, I still haven't missed 600 once, and paying so much attention to what the shot is doing is the reason why.
Also, a lot of work and years goes into being able to really read ball reaction well. It's pretty easy once you learn how, but it's really hard to explain in words without having visual examples. It also takes being very honest with yourself about the quality of your shot. For instance, if you throw a bad shot, and don't recognize it as that, but move anyway and then throw a good shot, the ball probably won't end up where you want it to.
