why does everyone find simple stuff so damned hard?
ok first thing. make sure the engine is warmed up and the oil is at normal cruising temperature. it is pointless leaning a cold engine.
establish in straight and level cruise.
look at your rpm dial.
slowly pull out the mixture knob watching the revs. they should increase about 50rpm until optimum mixture is achieved then the rpm will fall off.
push the mixture back in until the peak rpm returns. then screw in (richen) the mixture two turns and leave it at that.
if you change altitude or you need to use carby heat just push in the mixture knob and then do it again.
in a properly sorted engine you dont need EGT gauges. you can do it quite adequately watching the RPM.