Can you use Windolene wipes?

My Jumper or something

But I have a k800i. All the reviews say it's hard to clean and they're right. Even after you've wiped it with something, you can still see all the smudges.

My thumb

I use spectacle lens cleaner spray.... and a lens cleaning cloth. Clean it whenever I'm cleaning my glasses. (clean my glasses first, obviously, then its easier to see the muck on my mobile screen!)

I keep the screen cover on it which it came with.

the screen cleaning cloth that came with the phone.

Would windolene wipes damage the screen?

there are many solutions and screen protector available in the market but quite few are original that worth to get

Furniture polish

Are those screen protectors like the one that comes with the phone? If so, they would affect the picture quality.

Never had problems cleaning the screen of my K800i, just use a dry piece of cloth.

The K850i is more fiddly as in between the keys get dirty with use.

Not that I can see; I have a Viewty and the quality appears to be fine (and the screen is a bit important!) - it's not blurred or anything.
The most important thing with screen protectors is to apply them properly or, (like me!) you have bits of dust trapped underneath.
And make sure you buy them for your phone if the camera is on the front or anything would be affected by a piece of covering plastic.

lol haha

I would probably get bubbles under it when applying it.

my sleeve

My jumper or my trouser leg. (whilst I am wearing them)

I have some special wipes for my Macbook called iClear or iClean (something to that effect).

I use those for my iPhone screen. Work perfectly and make it look brand new.

Until I use the phone again, lol.

Nail varnish remover.

Baby wipes work great, buffed up with either your sleeve or a specs cleaning cloth.