Footwork? Quick like an antelope or
flat footed like an elephant?
If the latter, hit anywhere on the court where there’s open space. In singles, look to finish points a bit faster by getting to net.
For doubles, expose the player who is slower (usually there will be one) and make them move.
Serves weak or strong?
If weak serve, hit the aggressive shot and go down the line. If playing doubles, make sure your partner is aware of your strategy, so they're prepared to cover the middle and put the ball away. Keep returns low and away from the net player against a good server.
Win or lose the coin toss?
: If you win the coin toss and the opposing has a weaker serve, let them start the match. If playing outdoors and you lose the coin toss and opponent wants to serve, choose the side where the sun is at your back and/or wind is in your face. In other words, make opposing serve into the sun or with the wind.
Above all else, whether you're playing singles or doubles, support yourself and/or your partner. This is the cardinal rule of tennis and should never be broken!