Might be a silly question

[Za Za Bazaar]

but when playing any mission i only ever can keep 1 harvester and not produce enough to actually make any decent money for units, am i doing something wrong?

[Noodlesocks]

You can build more harvesters from the war factory or by building another refinery.

[Bronichiwa]

You can build peons from the warfactory (or whatever the name is). You can also build multiple refineries which come with a guy I think? I have 2 per harvester usually.