1- Know what to serve and when. If youve missed a serve because of high tension, it is more likely that you will not have the regular control and fluidity to execute your master serves. This is the worst possible time to launch an offensive using your tough and tricky serves as the chances are quite high that you may miss again. Stick to the safe short or medium, neutral serve.
2- When you arent playing, use that time to watch your opponents. Take a good look at how they play and what openings you can exploit in their game. Studying how they serve, how they return a serve and what are their strong and weak points will give you the winning edge, no matter how highly ranked they are.
3- Keep on attacking right till the end. Just because you are leading, dont make the mistake of playing passive and hoping for your opponent to miss a shot so that you could win. If you do, the tables could turn very quickly and you could find yourself at the losing end.
4- Develop various styles of serving with differing lengths and spins. Mix them up when you play. Some of the more complex serves include pure spin, medium-long, short , deep, pure speed, down-the-line....