It sounds like you're a bit of a beginner. If that's the case, leave strategy aside for now and focus on pocketing balls. I know the strategy behind each game can get fascinating and can often be the determinant between winners and losers but as you progress through your salad days, the best strategy often goes back to the fundamentals - make the ball.
I've been instructing & coaching players for a long time now and often the most difficult student to teach is the beginner that looks to play defense for fear of missing and losing the game. This strategy might help you against other beginners but it will prove to be insufficient as you progress through the ranks. If you want to improve quickly, treat pool like a shooting gallery. Knock everything down in front of you and you'll see your speed, selection and cue control naturally improve. Once you reach a level where pocketing comes more naturally, you'll then get to deploy strategy as a mechanism to gain control of the table and convert that opportunity into a win.
