Doubles Principles:  HAF HIC
We're all a little hick sometimes. Use Half Hick to remember:

High/low

When the ball is low you have to play it up. Play the ball to the opponent furthest back.
When the ball is high, be offensive and take out the net player (if you want).

Anticipate/Action

Anticipate where the ball is going by watching your opponents movements and the angle of their racquets. The ball's direction is determined as soon as it is hit and that's when you start moving to where it’s going; in if it's a drive and back if it's a lob.

Follow the ball

Think of the ball as a magnet and you are a piece of steel, the ball is going to pull you laterally, side-to-side, with each shot that is hit. Both players, 12 feet apart, cover the middle move with the ball.

Hot seat

The hot seat is around the service line. You are only there a split second. You either close in to be aggressive or back off to be defensive.

Insurance

Defense against the lob: When you are at the net and an opponent lobs, both players react by starting back. The person being lobbed makes the call "mine" or "yours" Ideally the player being lobbed is able to hit an overhead, both players return to the net. If they must let the ball bounce, both players retreat. If the call is "yours" that's your insurance, cover their side while they get your lob.

Close

The closer to the net, the more angles you have to hit a winner. The key to closing is timing. Anticipate and move on floaters. The closest person has 1st rights on every ball; be thinking
" this one's mine". Go get it and volley a winner.