This is question I get asked a lot, how do I stop double faulting under pressure ? Here’s what you need to remember.
1) Your first serve and second serve racket speed must be the same, you do NOT slow down the racket on the second serve, you simply change the angle of the face
2) You must drive up to the ball, don’t let the ball come to you. Under pressure the legs stop moving as effectively so make sure you’re jumping properly
3) Make sure your ball toss is consistent, if it’s bad catch it and start again, there is no limit to how many times you can catch it. It’s in the rules
Hope this helps !