An automatic watch is a small mechanical machine, and a little care keeps it running well for years. None of this is complicated — here's everything worth knowing.
Wearing and winding
An automatic winds itself as you move, so regular wear keeps it going. If it's stopped, give the crown 20–30 turns to wind it, then set the time. If you haven't worn it in a couple of days, expect it to have stopped — that's completely normal, not a fault.
Setting the date safely
If your watch has a date, avoid changing it in the hours around midnight (roughly 9pm–3am). That's when the movement is engaging the date change, and forcing it manually then can damage the mechanism. Move the hands to mid-morning first, then set the date.
Storage
When you're not wearing it, keep your watch somewhere dry and padded, away from knocks and dust. A lined watch box or travel case protects the case and crystal and keeps everything in one place — especially useful if you rotate a few pieces or travel with them.
Keep it away from magnets and shocks
Strong magnets (speakers, laptops, magnetic clasps) can throw off a mechanical watch's timekeeping. Hard knocks aren't great either. A sapphire crystal resists scratches well, but the movement inside is still mechanical — treat it with a bit of sense.
Cleaning
Wipe the case and crystal with a soft, dry cloth. For a steel bracelet, an occasional gentle clean with a barely-damp cloth is plenty. Avoid harsh chemicals.
Water
Treat your watch's water rating conservatively. Unless a watch is explicitly rated and tested for swimming or diving, keep it away from showers, pools and the sea — splashes and hand-washing are a different matter, but standing water and pressure are what cause problems. If you're unsure of the rating, err on the dry side.
Servicing
A mechanical automatic benefits from a service every several years to keep it running accurately — the same idea as an occasional tune-up. In between, regular wear and sensible storage are most of the battle.
That's it. Wear it, wind it when it stops, store it somewhere safe, and it'll look after you. Browse storage and travel cases, or explore the automatic collections if you're still choosing.