There is no easy way to improve; the best way to improve is to focus on the weakest aspects of your game and constantly work at developing these weaknesses. It is important not just to do drills you are comfortable with and not to play matches only with higher level players. Focus on the drills that give you the most trouble while fitting your style, and play matches with players of a variety of levels, as is likely to happen in tournaments. Doing drills you are unaccustomed to can seem cumbersome and physically draining, but keep at it and it will help your game a lot in the long run. Also, when you play against lower level players, work on keeping your focus for every point during the entire match. It will help you concentrate during the critical moments in tournaments and prevent losing easy points that could have been won. Good luck.