Putting the opponent under constant pressure during the baseline rally should be the main purpose for every tennis player. Of course, it is possible to win matches by just hitting the ball back into the middle of the court, however, we all should try to improve our attacking game, in order to become better tennis players and win more matches.
The most common way of taking an upper hand in a baseline rally is to change a direction by hitting down the line. However, it is not an easy shot to make and you have to choose the right moment when to go down the line, in order to avoid silly errors and put maximum pressure on your opponent.