Great warmup set in the pool
As someone who swims vertically, I hacked this warmup into the plans. The thread is on slow twitch right now, and IIRC some members asked about it (before my layoff). This works great before the EN swim sets, and the positional feel you get helped me a lot with speed (and then I separated my shoulder). This is as much for my own reference as yours 
150yd/100yd/50yd, on the 2min, 2:20, or 2:40 base.
50yd kicking, scissor out, dolphin-then-scissor back, with kickboard, with fins if needed, on whatever base needed, leave in soonest top.
Note: I liked doing the kick sets on my back, no fins. It really helps you figure out position.
50yd semi-catch-up, no fins, leave on soonest top.
50yd one-arm pull, no sculling with off-hand, with fins if needed, leave on soonest top.
50yd kicking, scissor out, dolphin-then-scissor back, with kickboard, with fins if needed, leave on soonest top moving right into this set all over again.