well, on the PS3 I find that the line it picks out for you when your shot starts only needs to be fine tuned about a third of the time. Also, to get a shot with a decent amount of power, instead of flicking the stick quickly like for bowling, you should bring the stick back, pause for about half a second after it is fully drawn back, then push forward. This will mean you will at least hit what you are after! The other thing to look at is the spin, on some shots adding spin is very useful, so experiment with different spins by moving the cue tip to different parts of the cue ball in the first part of taking a shot. Cue at bottom will produce backspin after the target ball is hit, top will make the cue ball roll forwards after hitting, and right and ball will go right etc.
Hope that this helps!