Wind a hand-wound watch at the same time each day, gently, until you feel resistance. Do not force it past that point.
Keep watches away from strong magnets: speakers, laptop lids and phone cases with clasps. A magnetised watch runs fast, sometimes by minutes a day. It is easy to fix and we do it free.
Do not set the date between about 9 pm and 3 am on most watches, while the date mechanism is engaged.
A full service every five to seven years keeps oils fresh and gaskets sealed. Sooner if the watch starts to lose time or power.