Before catching, I always got someone to grab 4-5 balls and bounce them in on me. 5 middle, 5 left, 5 right, 2 severe left, 2 severe right, then 5 mixed. Then I'd lightly stretch a bit.
Aside from that, I'd take pre-game infield. The coach would roll a few bunts out for me to throw to first and third. The biggest thing the coach would always remind me of is to not sail the ball. If it's low, it can be dug out. If it's high, your team mate will not be able to have a growth spurt by the time it reaches him.
When warming up the starting pitcher, I always wanted him to spin a few curves into the dirt for me. One, it gave me some practice and two, it gave him confidence that he could throw low with confidence, even with runners on base.