I just use plain water with Nittaku cleaning sponge after every day that I play. Once in a long while, I would add a tiny bit of dishwater detergent if I feel that too much oil from my hand builds up on the topsheet. That's pretty much it.
I grew up playing Friendship 729, Friendship Tackspeed 2000, Globe 999 and Juic 999. Nowadays I use hurricane 3 and Sanwei Target National. My way of cleaning these topsheets has remained the same over the decades. To me, if it ain't broke, don't fix.
I don't use clear cover sheet to cover those Chinese rubbers for two reasons: 1) when H3 used to be very very tacky, you would actually intentionally break the rubber in over the course of two weeks to make sure the extreme tackiness wears off (so using a clear cover sheet to cover those Chinese topsheets "kind of" defeats the purpose of breaking the rubber in and let the extreme tackiness wears off, so it is a habit) and 2) I am too lazy. If the H3 or Sanwei Target National lose way too much tackiness, it is time to get rid of it anyway. Buy a new one and move on.