Do not lecture about the contract. Constant reference to the contract will build anger and resentment in your child.

Monitor your child’s behavior and activities.

If your intuition tells you something is wrong, it probably is. There is no need to wait for proof. Trust your instincts. Act now!

Enforce the contract. If your child violates the contract, enforce the consequences immediately!

Do not allow your child to renegotiate the terms after the contract has been violated.

Use escalating consequences. Start with one of the least-severe consequences and increase severity as necessary.

If the contract is violated and a consequence has  been instituted, then negotiate a new contract with a more severe consequence.