Do as much as possible before. That way, you get to interact with your guests, enjoy your time with them and be present.
Hearty things such as stew are easy to cook the day before, and it actually tastes better the day after, because all the flavours have absorbed into the stew.
Half-cook the fish before the event, then finish it off when the guests arrive, so it’s nice and hot but not too well done.
Desserts are easy to make the day before.
Gadgets such as warming trays are a blessing. Once the food is ready, you put it on the warmer, and your guests can serve themselves from there. Little things like that make entertaining a lot easier.