I would like to know what recommended in 6 max micro stakes cash tables
Open with top 15 or top 20 or top 25 ?
At the micro stakes i'd be playing mostly value combinations exploitatively. Your opponents don't fold enough.
Also, if you're learning you should learn all the correct value lines post flop before balancing with bluffs. You won't lose as much money that way while you learn.
Get a GTO book. Maybe something mathew janda wrote. Don't copy his ranges they aren't great. Just learn the math concepts so you can build your own ranges when you move up the stakes.
My history is multi-tabling 6max 200NL on Stars.