The essence of "the proper procedure" is to handle the stored fuel pressure
in the lines - about 40 psi for multiport injection. It isn't a big deal
unless it takes you by surprise.

The classic way of doing that is to disconnect the fuel pump and try to
start the engine - it will sputter when the pent up fuel is injected then
just crank. As long as there is enough ventilation you can do it my way -
wrap a rag around the connection when you loosen it, then take the gas
soaked rag outside and dump a glass of water on it. The amount of
pressurized gasoline will be a couple of spoonfulls.

Mike