One thing that seems to be very upsetting to photography enthusiast everywhere is this: Why is there dust in my camera lens and how can I get it out!
It's understandable that after spending so much money on a good camera lens that a person would be upset to see specs of dust invading your precious property. However, it's important to know that any energy spent worrying about dust in your lens is unnecessary.
I know it goes against natural intuition. So much technology and design goes into the manufacture and design of the modern camera lens that you would assume dust seen inside a lens would hurt it's performance. Actually, dust inside a camera lens has almost no effect on the pictures that you take. The glass lenses work together to form a sharp image at the film (or sensor) plane; the quality of this image has to do with the shape of the lenses and how they work together. If there is a spec of dust on a lens, since it is not located anywhere near focal node points, it will not show up in your final images.
In certain situations, dust might be visible, but they are extreme examples. If dust is prevalent at the center of the lens, then pictures taken at a small aperture may make dust spots visible. From my experience, this is theoretical only. Upon selling one of my favorite lenses, a Nikon 105mm macro, I looked in the end of the lens to check the condition. I was so surprised to see it with many dust specs throughout the lens. I have taken some of my favorite pictures with that lens and you would never see any evidence of dust in the images.
I hope this advice doesn't come off as too harsh, but here goes. The best way to deal with dust in your lens is to quit looking inside the end of your lens! Since dust inside has no effect on your image quality in most situations, don't worry and obsess about it. My current lens, a Canon EF-S 17-55 f2.8, has a reputation for being a dust magnet. It has turned out to be a great lens that I enjoy using every day. The images look sharp and wonderful, so there is no need to look in the end for dust specs. I peeked once when I wrote this review and was curious; it turned out that the lens had picked up a few specs, but nothing I will ever worry about.
OK, if you absolutely have to get the dust that is bugging you out of your lens, the best thing to do is to take it to an authorized dealer for your camera manufacturer - they can send it to a qualified repair center to take it apart to clean.
I can't recommend taking the lens apart yourself unless it is a lens you absolutely don't care about or it is a very cheap lens and you just like taking stuff apart.
Just because dust isn't a big problem doesn't mean that you shouldn't take a few precautions to keep your equipment clean. The biggest thing you can do is to keep the front element (that faces the world) clean by occasionally wiping with a lens cloth. Take effort to wipe so that you do not force dirt underneath the dust seal at the edge where it can make its way into the lens.
Also, if you keep your camera in a bag, vacuum the bag out and keep it clean.
Most people would advise you to keep a lens cap attached to keep dirt out. Honestly, I hate lens caps as they slow me down and I never forget they are on until I am trying to take a picture. For my use, I never use a lens cap and have not seen dust accumulation as an issue.