There are obviously a variety of grinders on the market. We currently have Russell Hobbs battery operated grinders, which were a present I gave my hubby for Valentine's Day a few years ago (he just LOVES pepper).
The first golden rule for any salt and pepper grinder is to NEVER use it over a frypan of cooking food. The steam that is rising can get into the grinding mechanism, and over time the moisture can build up and ruin your grinder. This is especially the case with salt grinders, as the combination of salt, moisture and metal have the obvious end product of corrosion or rust. Therefore, if you wish to grind fresh salt/pepper into cooking, be sure to do it onto a plate and then tip the plate of freshly ground condiments into the pan.
The second tip I have is to regularly oil any metal parts that you can on your salt grinder. This lubricates the metal and reduces the opportunity for corrosion or rust to form on your grinder and its shaft and/or mechanism. Just put a little vegetable oil on your fingertips and rub it onto the shaft and screw top lid areas every so often. The best type of salt grinder to buy is one which has a plastic or ceramic mechanism, these are both great non-corrosive options.
Tip number three - never wash your grinder by immersing it in liquid. Simply wipe out the grinder if you wish to clean it with a damp cloth, and allow to dry completely before refilling with salt/pepper.
And finally, it is important not to use Rock Salt in most grinders. It is just too hard on the mechanism. Coarse sea salt is just as tasty, and doesn't take the toll on the mechanism as rock salt does. Try to choose the softer option next time you buy a top-up for your grinder.
So, there you have four really simple rules to follow to help maintain the life of your grinders. Your job today is to check your grinders over, oil any parts that might benefit from it, and refill your grinders so that next time you go to use them, they are ready to go! Happy grinding :)