Here’s a recipe for Magic Wash, the all-purpose, superior figure wash made with Future Floor polish. All you have to do is mix this with a little paint in a shade deeper than the base coat, and let it flow into the crevasses of the miniature. It’s an especially effective technique when painting a large number of historical miniatures because things go so quickly.
Path of the Outcast has a nice illustrated tutorial on mixing a base set of GW paints to come up with OTHER GW paints. For example: Chaos Black + Sunburst Yellow + Enchanted Blue = Scaly Green
Here’s an article on priming your figures with artists gesso. I’ve actually been using gesso to prime my figures since the late 1970s. I only use it on 25mm / 28mm figures, though. With my 15s, it is much more efficient to use spray paint.
You don’t have to paint everything as though you were trying to win a Golden Demon. Here are a few tips on speed painting vehicles.
Massive Voodoo has a tutorial on lighting your workspace.