I have been shocked to see how photographers treat their gear, especially the lenses.
Even if you’re a hobbyist it should be your number one priority to clean your camera and lens regularly. It has a huge effect on the quality of your images and reduces the time you have to spend post processing your photos. However, using just a microfibre cloth to wipe your lens clean can scratch the surface of the glass badly, so be sure to follow these instructions!
To start, I always try to be in a dust free environment, and have an anti-static microfiber cloth under the equipment I am cleaning. This is really important because your equipment is going to grab all the dust that is in the air like a magnet every time you try to clean it. The way I do it is always go from the outside to the inside, meaning I always clean the outer part of the lenses before I clean the glass, and I always clean the outside of the camera body before I clean the sensor. This way I gradually eliminate the dust that is stuck to the equipment.
A few years ago I was introduced to a new product from Japan that was the answer to all the germophobes that were really concerned with all the germs computer keyboards collect. This cleaning compound is like a sticky jelly, with anti-bacterial properties that can be used on everything you want to keep clean and germ free. I use it on the outside of my lenses and camera body, always with the caps on, because it is not supposed to be used on glass.
Cleaning the lenses
Dust specs are really difficult to keep away from your lenses, and you should never try to wipe the glass off with a cloth like most people do. Wiping off dust might result in scratching your lens. The correct process should always be to blow it off first. You can use a blower or a compressed air can, and this way you remove the dust but don’t touch the glass.
Now the dust is gone it is time to clean eventual smudges or fingerprints you might have on the glass. My favorite tool for this process is the Lens Pen. It has a tip with a soft compound that is made to safely wipe the glass, without damaging it. After cleaning with the soft tip, you may use the anti-static brush on the other side of the pen to get rid of any dust that is still around.
I usually don’t use any lens cleaning fluid unless it’s really needed. Those kinds of chemicals are never good for your lens coating, but if your lens has grease smudges, then cleaning fluid and a soft cloth might be the only solution. Repeat that process on the glass on the other side of your lens, and while you’re at it it’s also a good idea to check the electrical contacts of your lens (metal parts on the back). Dirty or oxidized contacts are most often responsible for camera malfunctions or errors, so I always clean them off with a soft cloth.
Dirty lens caps are also something to keep in mind to clean, as they always end up in your pocket or at the bottom of your camera bag while you’re photographing, so they collect a lot of dust. It doesn’t make sense to have your lens all cleaned up, then cover it with a dirty cap, the same applies to the body caps.
Source: Digital Photography School