Trusting your technique is a must in all sports. To have this belief in your game you need to practice and also make sure your not practicing or making your faults worse than they are. The need for a coach or someone watching you or taping your practice is very important if your not achieving good results.
Snooker confidence is built from a good cue action and positive thoughts and a constant ability to have a consistent cue action. As i said in another post your sub conscious thoughts can control part of what you do so writing affirmations or having another plan to change them will help you achieve more.
See if you can realize what has happened when you do miss is also very important and write it down to work on.