As we get better at the game of tennis, it is natural to start thinking about more complicated ideas on the court.
Often, strategy and anticipating your opponent's next shot take over your thought process. Both of these things can be very important to your success in a match. However, your ability to utilize a strategy and to anticipate your opponent's shot are directly related to your execution of the fundamentals.
If you are hitting the ball solid with your normal swing, moving your feet well, and always expecting the ball to come back, you will definitely be able to execute your strategy better and even anticipate the most likely reply from your opponent. Your good, solid shots will limit your opponent's options on the next ball.
I recommend keeping your focus on watching the ball, preparing early by turning your shoulders once you have identified whether it is a forehand or backhand, and following through on your groundstrokes. Add recovering and being ready for the next shot to give yourself the best chance of performing well during the point.
Although these ideas seem very basic and obvious, following the fundamentals will be the key to executing your strategy and having an overall good performance in a match situation.