How to Maintain Your Ukulele
Playing your ukulele regularly is the best thing you can do to keep it in good shape. Ukuleles are meant to be played, and a good uke opens up (sounds better) the more you play it. That said, to keep your uke sounding good, a certain amount of care and maintenance is required:
Clean it after you play it. You can buy all sorts of fancy instrument-cleaning products, but simply giving your ukulele a quick wipe-down with a soft cotton cloth (avoid anything harsher, including paper towels) is all you really need to do. This wipe-down prevents your sweat getting mixed with dust and gunking up your uke.
Store it properly. Even if you never take your uke out of the house, invest in a bag or case. Even the flimsiest one gives protection from dust and light dings.
Temperature is the big issue with storage. Avoid leaving your uke in direct sunlight, steer clear of heaters altogether, and avoid leaving it in a hot car. Cold is less of a problem, but if you’re traveling by car, stow your uke inside with you rather than sticking it in the trunk.
Under normal circumstances, airlines let you take your ukulele with you on the plane. However, security concerns may force you to check it. If you fly with your uke, definitely invest in a hard case for it.
Maintain the right humidity. Wood is a natural, breathing material and reacts to the surrounding environment. Therefore, you have to be careful if you live in a particularly dry or wet place:
If the air is very dry, the wood on the uke can crack. Invest in a humidifier to avoid this problem. Just put this little device in your ukulele case and it keeps the conditions more uke-friendly. Humidifiers are simple and fairly inexpensive, and so if you’ve invested in a nice uke, the investment is worthwhile.
If the air is very damp, the uke can warp. Leave a silica gel pack in the uke case to avoid this problem, which is more likely with solid wood ukuleles because laminated ones tend to hold up better in humid conditions. Ukes quite often come with silica packs anyway, but they’re also cheap and easy to buy separately.
All this great info came from: