Gone are the days when kids could drink and trash the house. That is not cool nor safe. Twenty-first birthdays are less fraught with worry of being sued or someone being hurt.
Do be on the premises.
Give out your phone no. to parents.
Register party with the local Police.
Invitation not to be broadcast over social media. You don't want gate crashers.
Invite another couple to help you host.
Make it a NO BYO and strictly NO drugs party.
Host in a way that gives the guests an indication of how they behave.
Dress up smart. Use plates, glasses and walk around offering plates of finger food and, later, cheese toasties, birthday cake and soup/cocoa.
BBQ sausages and chops.
Cordon off sections of the house.
Have start and finish times.
Take car keys off drivers.
Allow guests to bring a sleeping bag and sleep over.
(Pay attention to guests being in a state of mind to be able to consent if they are couples.)
You can not be serving alcohol to minors.
Keep the menu full and the drinks simple.
Hire a drinks waiter (friend) with an RSA to serve non alcoholic punch, mocktails, and alcoholic punch, beers and cider to those with ID.
Your child and their friends don't NEED to be falling over drunk to have a great time.
Ask child about entertainment and decorations.
Go full on with those and the music, games etc.
Say YES to all fun games and music. Make a dance floor and disco ball.
At finish time call off drinks and assist those who are capable to their rides, taxis.
No more alcohol for those staying over.
Cook up a breakfast the next morning.
If you can not host responsibly, hire a function room in a hotel. The bar staff then have to control underage drinking. You could organise shared taxis and parents at pick up time.