Review your owner's manual. It should give you the best instruction for your set.
Use only a microfiber or 100% Cotton cloth. Do not use wood-based products such as paper towels or toilet paper, they could scratch the screen.
Do not use ammonia-based cleaners such as Windex, 409 or others. They could damage the anti-reflective coating on the glass.
Try first wiping it dry with the cotton or microfiber cloth.
If the problem persists, use a damp (water only) cloth to clean it.Wipe gently in the same direction.
Some manufacturers recommend using mild soap, but do not do this unless your manufacturer recommends it.
Do not switch on the TV till its dry
Tip:::One of the best products for cleaning LCD screens also helps to 'fill in' minor imperfections, at least temporarily is one designed specifically for Plexiglas/polycarbonates used in motorcycle helmets, motorcycle windshields and aircraft windows... Plexus. Clean with a soft cloth or microfibre brush to remove dirt, vigorously shake the can and spray a light coating, top to bottom. Wipe with a soft, lint free cloth (a Vileda cloth is perfect) in a circular polishing motion. I have maintained an NEC screen this way for years and it looks brand new. The Plexus is designed to fill in minor imperfections and though it must be renewed periodically will clean a dirty screen and make an old screen look new.
Warning:::There are some products marketed as 'plasma TV screen cleaners' or as safe for plasma screens that are not. Just because they call it a plasma TV cleaner, don't believe everything you read.