Good strategy! Other ideas:
Get a drink (like a diet soda or plain club soda with lemon or lime) and keep drinking through the party. It will keep your hands and mouth busy so it will be harder to eat.
Only eat what you put on a plate. Don't pick up food from a tray or a bowl and put it into your mouth. Having to transfer a food, like chips, onto a plate gives you an opportunity to see the amount you are eating and put a cap on it.
Don't carry an empty plate back to the table, risking seconds. When you're done with the plateful, put the plate in the sink and rinse it, or if they are disposables, throw it out. You're done.
Take small bites. Eat slowly. There is no rush.
Good luck!
Jay