When you’re attacking, it’s important to keep the shuttlecock going downwards.
From the rearcourt, play smashes and drop shots; from the forecourt, play net shots, drives, pushes, and net kills (when you get the chance).
When you are defending, you must actively seek opportunities to regain the attack.
The choice of attacking shot angles is one of the most commonly misunderstood areas of doubles tactics.
As a general guide, smashes and drops shots should be straight or to the centre (cross-courts tend to be suicidal).
With defensive shots, you have much more freedom to choose different angles. Whereas cross-court attacking shots are usually a bad idea, defensive shots are more about finding the gap — wherever it might be.
Since the attackers usually bias their position towards covering the straight shots, some of the best defensive shots by the straight defender are played cross-court.