i found it helpful not to promote to many Servs into Commoner or Citizens so that you wont be overrun with demands like luxery and Goods. Only promote if you need them for a spezific job/roll and you now can balance your village better. If you have a problem with your income it can help to promte a few more to get more taxes.
Additonal you should always look at the Immigration and keep it as high as possible.