Prepare as much of the meal as possible in advance.
Set the table the day before.
Take time to sort out the most agreeable seating arrangement. Try to avoid potentially quarrelsome or competitive pairings. Two generals together will have a good talk if they meet professionally and get along well together. On domestic social occasions, however, they are likely to be competitive. Likewise, although striving politicians or successful surgeons have much in common, their greatest similarity at your dinner table will be an equally savage competitive spirit so that each will want to be the authority on the same subject.
Take trouble over the drinks. The secret is to make certain that everyone has enough to become slightly less inhibited, but no one should have so much that they become drunk or even so uninhibited that an animated dinner party flirtation crosses the barrier and has serious intention. A couple of drinks before dinner will be necessary in any case.
A dinner party seems more festive if there are at least two different wines. People will drink less of a really good wine than if they think they are enjoying a table wine for quaffing.
Be careful when dispensing after-dinner drinks. And never press them on anyone.
Don't accept too much help. Guests feel guilty about sitting down while hosts do the work. One waiter may be helpful, but the evening may be ruined if the whole room is buzzing about like bees around a beehive.
However tired you are, try to wash up after the guests have gone home. There's nothing more depressing than dirty plates the following morning.