How hard can it be?
Revs
Torque
Throttle position
Do not push clutch to far as the clutch brake is engaged (stops input shaft from spinning to engage a gear when stationary as there are no synchros to do this)
Range change switch
Splitter switch
Gear stick or gear cable wear to take into account
Up hill
Down hill
Flat
Here is a bit of a brief on a clutch brake.
I’m sure we have all driven an older car with a non synchro first or reverse where it is very hard to engage those gears when the oil is cold and thick in the transmission.
A clutch brake would have been good, but I have never seen them in cars.