Use common sense in the care and maintenance of your binoculars. Always attempt to blow off any visible dust or dirt from the binocular lenses before brushing or rubbing anything on the glass of your binocular. Next, use a lens cleaning tool like a Lens Pen or lens cleaning cloth to gently wipe off any remaining marks or spots from the lens of the binocular.
You may remove stubborn dried water spots from the lens of a binocular by lightly fogging the binocular lens with your breath. If your waterproof binoculars are badly soiled, you can even clean them by placing them under lightly running water (to minimize any possible damage). It's best not to use your shirt tail or pocket tissue to clean your binocular lenses. These fibers may contain material which will scratch the coatings on the binocular lenses. Also, never use an ammonia-based liquid glass cleaner. This would damage the lens coatings. If necessary, use only a cleaning fluid intended for optics.
Note: Check your neck strap or harness strap and its attachments for wear or slippage, too. Though most of today's binoculars have rugged construction, you don't want it to come loose and hit the ground!