Here's a warm-up to improve side and angle movement. Two players pair up facing each other. One player will be rolling balls; the other will be retrieving them.
Retrieving player sets up in ready position. Rolling player may kneel or sit. Rolling player rolls ball out wide to retrieving player's forehand side. Retrieving player split steps, then steps out to retrieve ball and rolls it back, then returns to recover spot and ready position. Rolling player then rolls ball out wide to backhand side. Continue for X amount of reps or set time period, then switch roles.