Hey! It can be a tricky area to practice because everyone has different serves and some yoh will find easy and some you will struggle, but playing against a good mix of players helps to get to play all different serves. The best drills are random ones where the opponent can serve all their best serves because that’s what will happen in games.
If you want to make it more structured then you can select different returns to work on at a time, for example the serve a mixture of serves to the short forehand and you try to work on a better push or short touch. Then maybe a mix to the backhand the same. Also doing this with your flicks and then mixing in long serves where you have to try to topspin.
I also like to practice being very aggressive on the returns and also keeping the ball very tight and stopping the opponent attacking, this is the 2 areas where points can be won and lost mainly on returns.
Let us know if you have any other questions on this. Dan 🙂