At different levels, players need to focus on different things to improve. Here's a rundown.
- Beginners: Fundamentals, Fundamentals, Fundamentals! I can't get any more specific than that. Develop those fundamentals until you can do them in your sleep –strokes, footwork, serve, and receive. Work with a coach to develop them, find players to practice with, and drill, drill, drill!
- Advanced Beginner: Playing Style. At this point you have at least semi-mastered the basic fundamentals, and should be looking to develop a playing style. But keep harping on those Fundamentals, Fundamentals, Fundamentals!
- Intermediate: You now have a playing style and have somewhat mastered the fundamentals. Now you should be really honing your playing style, as in what shots you should do and when. Your serve and receive game should directly be setting up your game. You should be figuring out what you win and lose on, and work to get rid of weaknesses while making your strengths overpowering. But guess what? You still are not advanced, and so you need to continue to focus on those Fundamentals, Fundamentals, Fundamentals!
- Advanced: You have mastered the fundamentals, though (brace yourself) you should continue to work on them as long as you want to improve – the more consistent they are, the better you will be. But you also need to really develop all parts of your game so that you are the master of any situation and against any style. You need to constantly examine your game and your matches and figure out what you are winning and losing on, and train to overcome any weaknesses while continuing to develop overpowering strengths. You have fewer rivals now – you've left most past ones behind – so at this point you should be studying rivals to find specific ways to defeat them.