I bought a shredder from Amazon, that could shred cardboard and all the boxers you get from them, old letters, the fre newspapers, junk mail
I have a hot bin, so pretty much everything goes in there, they say you can put food waste, but I've never tried it
It seems to grow a white fungus as it starts rotting, I have been told this is normal
When I cut the grass, I put that into a black bag, then everything in the shredder, give it all a good mix up, I probably use a bit too much paper/cardboard, because I never get any 'liquid gold' leaking from it (no idea what that even means)
When I open the panel at the bottom, I scrape it out, it is very wet, but no smell, spread it out, dry it, then sieve it, bag up the good stuff, what hasnt rotted away goes back in the bin
During the winter its just paper/cardboard that goes in there, plus whatever veg waste we accumalate