Two ways—have everything done before the guests arrive, and invite people you want to see.
By being organized. You cannot have fun if you're stressed, and unless you're organized, you will be stressed. Before the doorbell rings, I like to make sure all the lights are dimmed and the music is on and the candles are lit and my table is ready and my food is complete.
If you're having a lot of people and you want an amazing menu, definitely don't cook everything yourself. Either have people help you or mix store-bought items with home-cooked ones. And set up a self-service bar, or have a bartender, so you're not the one making the drinks and serving everyone all night.
Sometimes I'll order the best dish I've had from a bunch of different restaurants that deliver. Then I'll dress the table beautifully. I'm not afraid of using the containers the food came in—I'm not trying to tell anyone that I cooked it.