On the serve, placement is more important that power. You can have a huge serve but if it is predictable, your opponents will be ready for it no matter how hard you hit it. Moving your serve around is extremely important. If you’re having trouble placing your serve, start at either side of the “T” (the service line), and serve to spots (the shorter distance will make placement easier). After you develop a feel for serving from the “T,” back up until you’re in between the service line and the baseline and repeat. Finally, move back to the baseline and slowly incorporate your full motion. Do this for different locations and your service placement will be much improved.