A very experienced player said the service and the return of serve are the most important shots. So I would like to serve as well as possible, but I don't know what I am aiming to achieve. I try to serve so the shuttle goes close to the net and lands close to the T, occasionally I serve wide, quite often I have success by placing the shuttle immediately in front of the receiver.
What else could I do, what are the criteria for a good serve?
Apart from the obvious, dipping under net level which visor described, a thing people sometimes forget that is equally important in doubles is reading the positioning of your opponent. Sometimes a serve 10 cm to one side will cause the player to lift instead of push because of uncomfortable position of the racket. A lot of double players serve the same way with the occasional flip, but having three, four positions for your short serves is very beneficial. It might not be as important at the very highest level of men's doubles where the shortest path is almost always the most effective, but in other skill levels I believe it's very important.
in doubles, you play 95% short serves.
in principle, you always serve to the middle and as short and tight over the net as possible.
if your opponent starts to attack those serves, you start varying to serve a bit to the left and right (by a little i mean: 30-50cm is enough!). still as short and tight as possible.
you throw in a flick serve from time to time (means once or twice per set!).
best tipp für beginners/intermediate players:
concentrate on one serve: a short and tight serve.
and practise, practise, practise. the importance of a good serve in doubles cannot be overrated!! it wins and loses games! don't think too much about variation, more about precision and consistency.
Three more things: A tighter stringbed will give more accurate and consistent serves. And to start with you only need one other variation, the flick serve. And to make the flick serve more deceptive, you have to make it with exactly the same preparation as your short serve.
Another element besides the quality of the serve itself is looking to intercept and or attack the return. By serving in certain positions or observing how the receiver is holding their racket or standing you can sometimes anticipate the most likely return.
Thanks people, that's encouraging, my serve is pretty consistent and precise, I will continue to work on that but focus mainly on other areas where there is more room for improvement.
The consistency and precise is a must. I mentioned speed, or changing of speed, because good players will adapt to the tempo of your serve - even when it is tight. You want your opponent to know you can change angle, speed, and flick.