Mushroom growing is so diverse, there are many types, various growing methods for each type and to make it complex within one type the methods are so numerous.
There are various substrates that can be used for growing mushrooms. Some substrates can be used for various types whilst some are limited to other types, but with mixing and supplementing one basic sustrate can be used for various mushroom types. Substrate choice depends on where you are, a substrate used in China may not work well in Zimbabwe or its not even avalable at all. For instance Chiredzi has abundant sugarcane waste which you do not get in Harare. In short use a substrate that is available where you are.
One of the most important steps in substrate preparation is wetting it, this step seem to be easy for those using hot water bath although their chalenge is on draining the excess moisture.
Reaching the right moisture content is achieved from experience. Even experienced growers sometimes over/under wet the substrate.
In the photo I was wetting cotton waste, all cotton waste based substrates are hard to wet because cotton doesn’t easily absorb water, when you look at the surface you are tempted to add more water and the water has accumulated underneath. Once its over wetted cotton waste is hard to drain.
It is also impontant to know the nutrition available in the substrate so as not to have too much nutrients which will cause contamination or too little nutrients which result in poor yield and unheathy crops.
The structure of the substrate must allow air to pass because oxygen is required by the growing mycelia.
In some cases it is important to supplement substrate with highly nutritious substrate and also add additives such as lime,gypsum and other additives depending on type grown.
The above list of tips and ideas is not exhaustive, there are many things to be considered
What kind of substrate are you using to grow mushrooms.