Cleaning a camera lens requires special care to avoid scratches and other damage to the camera lens. Unlike your sunglasses, you can't simply rub a camera lens with your shirt tail without leaving scratches that permanently affect image quality. Have a projector? It's important to clean projector lenses too.
Dusty LensPXHere/Public Domain CC0
If you've used the lens in a dusty environment, remove the dust from the lens using a soft brush. Wiping the lens with dust still on it could scratch it. Gently brush the dust from the middle of the lens to the edges. Then dislodge the dirt from the edges by holding the camera upside down with the lens glass pointing toward the ground, allowing the dust to fall toward the ground as you brush. Use a brush with soft bristles.
Bulb BlowerPiotr Siedlecki/Public Domain Pictures
If you'd rather use something that doesn't make any contact with the lens, try a bulb blower or air bulb. It delivers a small puff of air without adding harmful moisture. Don't use your mouth or canned air. Blowing on the lens with your mouth could dispense saliva. Canned air can sometimes spray liquid difluoroethane, the liquid form of the gas used to deliver the air. Also, canned air can sometimes carry so much force that it can drive dust particles inside the lens housing, especially with cheaply made lenses. With a few gentle puffs from the bulb blower, you should be able to get most of the debris off your camera lens.
Microfiber ClothDavid Bicker/Pixabay
After removing dust, probably the best tool for cleaning a camera lens is a microfiber cloth, which is a soft cloth that you can find for less than $10. It's made specifically for cleaning the glass surface on camera lenses and even glasses. It works well for removing smudges, with or without lens cleaning fluid, and a microfiber cloth can clean other parts of the camera, too. Start wiping gently in the middle of the lens, using a circular motion as you move toward the edges of the lens.
Cleaning FluidGeorge Hodan/PublicDomainPictures
If you cannot clean the lens adequately with the brush and a microfiber cloth, try using a few drops of lens cleaning fluid. Always place the liquid on the cloth, rather than directly on the lens. Excessive fluid could damage the lens, so start with a few drops and increase the amount of fluid only if needed. Most simple smudges will come clean easily after just a few drops of liquid.
Plain WaterAxelle B/PubicDomainPictures
In a pinch, use water to dampen a piece of tissue paper to clean the lens. Avoid using a rough cloth, such as you find with some types of t-shirts, or a rough paper towel to clean the lens. Additionally, do not use a tissue or cloth with any lotions or scents in it, as they're more likely to smear the lens than clean it properly.
Get a GripATC Comm Photo/Pexels
No matter how you choose to clean your camera lens, maintain a good grip on the camera or the interchangeable lens. If you're trying to hold the camera or lens one-handed so you can clean the lens surface with the other hand, you could potentially drop the camera, leading to a broken lens. It's best to hold the camera or lens directly above or even resting on a table or counter surface, so if the camera does slip from your hand, it won't fall to the ground.