There are several ways to serve a ping pong ball. I have noticed that some serves are far more obvious to read/understand than others.
For example, if a player contacts the top of the ball during the serve and flicks their wrist toward the opponent, it's obviously going to have a lot of topspin. Likewise, if a player contacts the back of a ball and pushes downward during the serve, it's high in backspin.
When watching a match between colleagues last week, I noticed a really interesting legal serving technique. The server threw the ball up fairly high, placed their paddle directly under where the ball would land between the ball and the table (almost on the table), and then chose a direction to flick their wrist. The time right before the ball hit the paddle, some side spin was usually added with a wrist flick. I found this serve really hard to read because that last moment of the wrist flick was very quick and sometimes hard to see/obstructed by the ball. This server's grip was a variation of the penhold grip.
Does anyone have any tips for making a serve less predictable/readable? My goal is to give my opponent as little time as possible to decipher what spin is on the serve until it gets to them.