Jim Loehr was the first to study this systematically and come up with stages of inbetween point behavior. Basically you ritualize your body posture, your movement and your thinking to maintain a positive physical and mental orientation throughout the ups and downs of matches.
It's been picked up, studied, expanded, refined, etc by other experts like Jeff Greenwald, Allen Fox, and Alistair Higham.
All those guys have books or dvds if you search. They all also have article series on Tennisplayer.