Tennis is a game of trial and error. Most players have a certain strategy or specific shots that they like to use. Because every match is different, it is important to pay attention to what is happening so you can adjust your ideas based on how things are going.
If your crosscourt forehand seems to be working, and it is helping you win a lot of points, keep using it. If your strategy or a certain shot is not working, make an adjustment or change your idea slightly. Sometimes a certain play will not work initially but becomes more effective the longer it is used. Don’t completely give up on something if it isn’t instantly successful. Try some other things and then go back to the idea. Each point that you play will help you learn what may work and what you might need to stay away from.
Try to be a student of the game while you are playing the match and find out something helpful each time you play a point.