Example: They don't want to brush their teeth? Fine! After a few months let them see how they like it at the dentist's... (of course, this also needs to be age appropriate, obviously).
There is a book "The Entitlement Trap" which has a very elaborate scheme to get rid of all possible reasons for fighting, if you wish to go this way. Some people may think all of this is too much "capitalism", but if you are not against that out of principle, their "game rules" certainly are logically watertight. They also manage to put a lot of positive connotations into the matter - i.e., it is a family activity, not just a payment scheme.