Anything aspect of modelling from the basics to advanced topics should be fair game.
Decaling, assembly, super detailing, using an airbrush, working with PE, working with resin, when and were to use different types of adhesives, painting figures, how to tell the difference between types of Shermans, Tigers, Phantoms. etc, using the internet as a research tool, making and painting groundwork or buildings, using specific types of paints (AlClad, acrylics, enamels, etc), weathering (filters, washes, pastels, pigments, etc), removing seams or scratches from canopies, filling seams, rigging ships or bi-planes, airbrush maintenance, painting woodgrain, masking for camouflage, modeling on the cheap, details judges look for at contests, photgraphing your models, adding lights and/or motors to models, ...
Cheers,
Rich