Taking more time is a great idea, and it can be very bothersome to an opponent, especially if he is she is not convinced that they will win the match. The other strategies you suggest are also very viable–but they depend on primarily one thing–that you be fitter than your opponent physically.

Fitness is one of the few things in competitive tennis that can be controlled by the individual. The fitter player has more Plan B opportunities. Generally as a player I would try, and tell my students as well, two main things when losing: do not beat yourself (no free points,) and make the opponent work as hard as possible for each and every point. These can make the opponent wear down either physically or mentally, and the match can begin to turn toward the fitter player.

Sometimes these don’t work–sometimes we lose because our opponent is just better. But there is nothing wrong with building a reputation as a “tough out.”