Before a game I'll plan a lot if I've had trouble with someone's serve in the past but once the game starts I can't tell them what to serve and I think it's dangerous to go in with you're mind cluttered on what you're going to do their serve especially if they then do something different to what you're expecting. You'll be confused, off balance and probably make a mistake.
Now I just tend to watch the direction the blade's moving in at point of contact with the ball, where the ball bounces on their side of the table and how it's bounced.
If I can't figure out what they are serving, I'll sometimes "give up" a point by just offering a dead bat to the ball to see what type of spins they are putting on it and try and adjust accordingly next time.
If that doesn't work I'd consider trying either
1. Hit through the ball hoping to take any spin I don't recognise off the ball which admittedly has a low percentage chance of success but may intimidate an opponent in to not serving that type of serve again or
2. Someone once told me a team mate of theirs always heavily top spinned the ball back regardless of the servers action - emphasis on spin not power. If the serve had bottom on his top spin would lift the ball back over the net; if the serve had top spin on, the ball would go back high over the net but kick on landing. Rather than use power, they used spin to counter spin.
Service return is definitely something I need to work on. The down side is that you need someone willing to tell you what spin they're putting on the ball and serve the same type of serve to you over and over until you figure out how to return it consistently. Most people I've tried that with either don't want to "reveal" their serves or get pleasure from mixing their serves up on purpose which is not what I asked them to do.
