Best way to start is to either buy premade mycelium bricks(all you gotta to is fruit it) or premade spawn & substrate(learn inoculation) Either will give you a easy look into growing. Also learn the equipment required for each process; A pressure cooker/sterilizer to make the spawn, and a pasteurization setup for the substrate. Also need various other equipments like a laminar flow hood/ or a Still Air Box for the actual inoculation.

Goes kinda like: 1.Make /source spawn(sterile grains/wood inoculated with spores/mycelium in sterile enviroment)

2.Make/source substrate(partially sterilzed to improve mycelium growth)

3.Add spawn to substrate in sterile enviroment(SAB or flow hood) and then seal.(We use filter bags&sealer but theres other options like sterile mason jars or tubs)

4.Let mycelium grow. Once growth has consumed substrate you expose to air(via cutting bag or lid off)

5.Fruit mushrooms in preferred enviroment(dependent on strain but usually humid with mild temp, in a clean room/box/closet)

Its alot of prep & cleaning to get to the final product and theres other steps you can add such as maintaining/ curating a stock of spores and mycelium strains to more easily make spawn.

We have a barn setup to make 2000lbs of substrate every other day(with agriculture type equipment) and our fruiting rooms are refrigerated semi trailers outfitted with shelvings, humidity and oxygen sensors.

We currently do blue oyster, yellow oyster, king oyster, lions mane, chesnut, cordyceps, reishi and shitake and are adding golden enoki next month. Also have semi-regular foraged chantrelles, CotW, and lobster mushrooms.

Sorry its a chaotic info dump but ill organize it soon hopefully

Ps

Theres another option which is you find a small local mushroom farmer and they usually give away their old mycelium blocks for donations. You plant a bunch of those in a garden and you get loads of free mushrooms every spring/fall. Which also reminds me i didnt touch on doing outdoor growing or log/plug spawn which can be fun too definitely worth researching if you have outdoor space.