Basic Tips
When your on a difficult pot, always try to hit the cue ball without any backspin, topspin or side. This will increase your chances of making the pot. When the distance between Cue Ball & Object Ball and Object Ball & Pocket is quite small, it usually doesn't matter if you play these shots with backspin or topspin.
When your aiming for tough shots, always set the power to 100%. This makes you able to set the aiming line with more of a "fine tune", making the set-up of the shot easier. When you have set the shot up, you can then set the power to what you want in the power bar on the right side of the table.
Using too little or too much power will decrease your chances of making the shot as this will change the direction of the cue ball slightly, but enough to miss the shot.
Try to keep the Cue Ball away from the cushion. When the Cue Ball is tight on the cushion, this increases the chance of missing the pot as the cue butt is raised and therefore even the slightest off centre strike will impart swerve on the cue ball, throwing it off line.
Noops says..
One of the shots that has a lot of players wondering how is the extreme fine cut. The shot isn't actually played as a cut. The secret is to play to miss the object ball, only by a fraction, and catch it on the way back off the cushion. To send the cue ball into the object ball you will need to apply extreme side. Obviously the side applied depends on the shot itself. The side applied will give the effect of cutting the object ball very thin, and should with a little practice become effective most of the time.
Another shot alot of players seem to wonder about is the Double Kiss shot. If the object ball is on or very close to the cushion and the object ball is straight onto it, you can play direct into the object ball and force a double kiss. This will send the object ball across the cushion and hopefully in. Needs a reasonable amount of pace, and side to throw the object ball in a ceratin direction.
LcMoNeY. says..
Cushion shots. loads of players lose games because of these type of shots. You need to know the nap. If aiming down towards the black spot, the nap takes the object ball to the right of the pocket, and to the left of the pocket if aiming towards the top of the table. Use little power, just try to roll it in. More power just makes the error lines wider then they are. I use 16 - 17 percent. If you think these shots are just random error, play this shot here 10 times as its shown, tenner says it go's 9 out of 10.