yeah, timing controls your direction of the ball...if you hit it earlier, it'll go one way,a nd if you wait a half second before hitting, it'l go to other way.
You can also lob the ball by doing kinda a upward swing to get it over the front opponent.
Also, if you time it correctly you can do a super fast serve every time. I haven't quite figured out how to curve the ball either yet, but I've done it a few times on accident.
Hope that helps though!