Water-proofing of your timepiece is the number one thing you must take note of. If unsure, use it assuming it is only dust-proof.
If you have need to change the time (traveling) or date (28th, 29th or 30th to 31st), do it only when the watch is dry. Remember to push the crown in fully after setting the time and/or date.
For screw-in type of crown, it is important to FULLY screw in the crown until it is tight. During the initial stage of screwing down, do not force if it feels jammed, unscrew and screw in again. Forcibly screwing in the crown can result in cross-threading and permanent damage to both the crown and case.
Water resistance is not permanent as the gaskets responsible for water resistance will harden and shrink over time and/or wear out with use.
If you notice mist under the crystal or signs of oxidation on the dial, bring your watch to us immediately without delay.