I can now answer that question as I am a compost millionaire, with more compost than I know what to do with. It has only taken me five years to master it, but hey ho. The secret recipe is below
1) Chop everything up small with a sharp spade or similar. This helps it to rot down quicker, but more importantly enables you to fork it and turn it over with out finding massive weed ‘spiders’ that get tangled to everything.
2) layer it up so you have carbon stuff and nitrogen stuff…dried and brown stuff mixed with green leafy or grassy stuff.
3) water it
4) turn it
The last one is the most important. If you do this it will rot down super quick (3 months), if not, it can linger around for years.
I have dismantled and rebuilt all of our 5 compost bins. The previous incarnations had been in situ since we moved in 5 years ago so were beginning to rot. I have moved them up and changed the design slightly to accommodate better compost making.
The main difference is the open fronts. This is to make sure that they can easily and regularly turned. Closed fronts encourage over filling and no turning, which means the matter does not break down.