If you’re stuck trying to figure out motivates your child look at how they spend their free time or spend their money as those things will matter to your child. Filling out the Finding a Meaningful Reason worksheet on Smarter Parenting will help you find out what is motivating to a child. http://www.smarterparenting.com/uploads/channel-files/170/worksheetcorrectingbehaviorsfindingmeaningfulreasonsmarterparenting_2.pdf
Consequences and effective rationals will improve the relationship with your child as your child will better understand that you understand them and are there to help them.
Giving meaningful reasons to your child will take some getting use to, but the dividends will pay off long-term.