There are two guiding principles when it comes to care and maintenance of your camera, lenses and filters:

• keep it clean
• be gentle

You are dealing with a sensitive optical instrument.  To operate as designed it needs to be kept clean.  Pick up a lint-free cloth and use it to gently clean your filters and lenses.  When you change lenses minimize the chance that any particulate matter (dust, ash, hair, etc) falls into your camera.  Angle the camera down and be quick about it.  Some references say that turning off the camera helps keep dust out since having a charge on your sensor will attract dust.  I am not convinced that this is the case, but I do think it’s a good idea to turn your camera off before opening anything.

On occasion you may notice small grey spots in your images (typically these are most noticeable on a field of uniform color, and typically that’s the sky).  These spots can be dust on your sensor.  Sometimes this goes away when the particle falls off.  If this continues you can try and gently blow the particle off.  To do this you need to lock the mirror in the “up” position (consult your manual for how to do this).  Note, as will be mentioned in your manual, that you need to have a full battery or be plugged into AC power for this – if the battery runs out the mirror will quickly snap back into position, and if you have something in its way this could result in significant damage to the camera.  Once the mirror is up and out of the way, take a “hand blower” (a bulb with a nozzle attached, looking similar to what you use to suck mucous out of a baby’s nose) and gently blow air into the camera.

If you still have trouble with specks on your images and you have verified that it’s not scratches on your lens, then you have three choices:

• clean the sensor yourself
• send it in
• deal with it

I have not attempted the first option.  You can make things much worse, and I don’t have near the finesse for it.  I have no experience with the second option.  If you opt for the third then be aware that there are two things which can help you.  Some cameras have a setting to collect “dust data” and will use it to subtract the dust image from the pictures you take.  Some software also gives you the ability to “heal” dust spots.  In general, try to keep dust away from your gear.

Whenever you’re dealing with your camera and its lenses keep in mind that these are sensitive optical instruments.  Minimize shocks and extremes of temperature.  Try not to move your optical gear from a very hot/cold environment to the other extreme, as moisture can condense, causing easily wiped off fog on a lens to not-so-easily-wiped-off fog inside your camera.  Remember that all the optics are precision-placed, so banging the camera against your car or dropping it on the floor can cause significant degradation of performance.

A good habit to get into to address all of these concerns is to keep your gear in your bag unless you’re using it.