I've been meaning to do this for a while now....there is always room for improvement. Feel free to add your suggestions.
First of all you need spawn. Spawn is basically decent amounts of mycellium colonised material. To get enough spawn together I place stem butts between layers of damp corrugated cardboard. After a few weeks the mycellium travels off the stem butts and onto the cardboard. The cardboard is then added to a bag with woodchips, sawdust, bits of hessian and smaller bits of cardboard (you can use hessian sacks or green bags...no need to be air tight but will need to be kept damp). The mycellium will then travel to the other materials. You can keep adding more and more and transferring colonised bits to other bags to increase the amount of spawn you have. The more spawn the better and it's always good to have several bags or hessian sacks full of woodchips colonising in the background whilst you go about life.
Once you have some spawn you can start a patch. I chose an area that gets lots of shade and also gets a lot of organic leaf matter naturally throughout the year.
next i covered the area with layers of hessian, some sawdust and pieces of cardboard that i had laying around. it's pretty rough but i don't think it really matters overall how even everything is.
i then added colonised bits of cardboard, woodchip and hessian. some i placed upside down and others i placed facing up. i didn't have huge amounts of spawn so i mixed it around as best as i could in different areas. ideally you would have bags and bags of colonised materials and you could spread it evenly. this way will still work it will just take longer to fully colonise the area.
i then added a layer of eucalypt mulch and a layer of pine bark mulch on top. this mix isn't set in stone and there are a range of different mulches you can use. i just happened to buy these two.
this is what it looked like once the top layer of mulch was added:
keep watering it over summer and checking every now and again to make sure the bottom layers aren't drying up.
cross your fingers and wait till next season for fruits!!