Clean gently and regularly rather than waiting years.

For lens dust, start with the least invasive method: use a blower, then a soft anti-static brush or lens pen. Only use a clean microfiber cloth when dust or smudges remain. For fingerprints or oily marks, use a proper lens-cleaning fluid made for camera optics.

For the LCD and camera exterior, use a soft microfiber cloth; avoid harsh cleaners.

The spots visible in macro photos are more likely from dust on the sensor than from the lens front element. On interchangeable-lens cameras, sensor cleaning may be needed occasionally; if you’re not confident, have a service center do it. Dust on the mirror can also be professionally cleaned.

Good habits help: use a lens hood for protection, store gear in a dry environment, and brush/blow off dust after shoots.

Avoid these on lenses and camera surfaces: canned/compressed air, tissues/paper towels/toilet paper, pre-moistened eyeglass wipes, window/ammonia cleaners, unknown liquids, anti-fog products, and water/saliva/other household liquids.