Not specific to this camera, but I always recommend bringing a small towel with you to put in your pocket. It's easy to remember things like not changing lenses on the beach (go back to the car or indoors) and not putting the camera on the ground/sand. However, if you sit or lay down to get a shot and use your hands to get back up, those sandy hands now have nowhere to go but your camera, negating all of the care you've taken. A little towel to brush off the hands is priceless. After the beach, a thorough brushing with a little brush (LensPen or the like) and THEN some work with a blower and your camera is as good as new.
Not specific to this camera, but I always recommend bringing a small towel with you to put in your pocket. It's easy to remember things like not changing lenses on the beach (go back to the car or indoors) and not putting the camera on the ground/sand. However, if you sit or lay down to get a shot and use your hands to get back up, those sandy hands now have nowhere to go but your camera, negating all of the care you've taken. A little towel to brush off the hands is priceless. After the beach, a thorough brushing with a little brush (LensPen or the like) and THEN some work with a blower and your camera is as good as new.
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I'd keep the lens cap on when not making pictures. I've been researching sensor dust for the x100S; fortunately I've found very few cases. The easiest entry point for foreign objects would seem to be the lens mechanism -- since the lens does have to move for focus adjustment. If you get dust on the sensor, the camera has to be taken apart to clean.
Naturally, keep it in a sealed case or bag that will prevent it from getting wet or touching sand -- and only take it out to make a picture. Air at the beach is typically humid and often salty. Overall it's not a great environment for any camera.
If you want to get one step further, buy an underwater casing. They don't mind sand and allow you to put the camera on the sand. Just make sure to rinse and towel the case first before you open it (in the hotel room)!