Python Plug-in

I tried making a plug-in from a Rhino.Python script (rhinoscriptsyntax), but I did not succeed.
All information I can find regarding this is at least 6 years old, fragmentary and thus not very clear to me.

Am I overlooking a more recent manual?
If not, would it be possible to make a new, extensive one?

How are you making your Python plug-in?

– Dale