brake adjustment 350cc

Any advice please. I have a 2001 350cc pod which the drum brakes need adjustment since it has has stood for quite a period. What is the best way to adjust, is there a knack ie, adjust on the rear of the drum until the brakes start to bind then back off, or done in mm lever adjustment???
Any advice appreciated as currently the pedal need quite alot of pressure and the brakes are not very good, either on or off, not alot inbetween.
All wheels/drums have been removed, all levers now move easily and the shoes expand, the shoes and drums have been scoured and no dust present.
Thanks