I play both indoor and beach. I haven't really done a lot of beach though, and I tell you what. Jumping on the sand is incredibly hard at first. Basically, the one thing I like to keep in mind is jump upwards not forwards, and swing your arms hard (important to get your non-hitting arm up nice and high to spot the ball).

Beach is great for your vertical though. Immediately, your vertical will go down, but after a while it'll skyrocket. Your calves will develop a lot also.