The best policy is not to make enemies out of your neighbors. Neighbors may not be your best pals but they deserve respect and courtesy too. If you're holding a party that may be noisy, give your neighbors their dues by inviting them too. That way, nobody feels hurt or offended at the happy noises generated from your party. Whenever you feel that your right has been violated, it pays to speak up promptly.
Fast action relieves pain and keeps grudges away.
Talk tactfully to the neighbor by addressing the problem. Don't attack the person. Personal criticism will be met by a defensive stance or worse, a heated exchange of words. It is safer to talk standing on neutral grounds. You can also talk at the gate or over the fence.