Course management can greatly improve your scores. Tour players have a strategy for playing holes on a course and so should you. Know what your handicap is and what your strengths are.
If you are a 18 handicap then you average bogeys on most holes. Bogey should be your par. You can lower your scores and handicaps by placing bogey as your target score rather than par. For instance, plot out par fours to reach them in 3 shots rather than 2. This will leave shorter and less difficult approach shots. The goal here is to remove big numbers which destroy your rounds. Most of the time the big numbers come from an errant shot on a long hole in which you are trying to reach the green.
Know your handicap and play for your par and you will see the big numbers go away and you will make more pars as a result and your handicap will go down.