Here's a drill emphasizing aggressive play. It focuses on serve and volley and can be especially useful for beginner or intermediate players who are timid about attacking the net.

In standard doubles court position, each player serves three times - trying to get in three hard first serves. After hitting each serve, the server immediately attacks the net. The receiver tries to pass down the line or up the middle (without lobbing). Play out the points. After three serves change to the next player. The serve, the attack into good net position, and return of serve are all practiced repeatedly in this simple drill.