One of the things I see in many matches is the underutilization of the service box. Player A serves from the right of center and hits drive serves left, right and a z serve right. This is a good basic offense for Player A.
Player B starts same as player A but then moves left of center, way to the right, way to the left. Player A has three basic serves.
Player B has 3 from position one, 3 from position two, 3 from position 3. Nine serves vs 3 serves. Now throw in a few different angles and a few different speeds. The serves have gone from 9 to 27 but they look basically the same.
This is the subtle part of the game that even the old timers sometimes miss. The subtle change of speeds and angles, and drastically changes the returns of serve.
Try using the entire service area for weaker returns!