I decided the fire wizard should reflect the colour of his spell. Namely, red. And the other fellow should naturally be watery colours, largely blue.
The fire wizard's cloak is painted in (lots of layers of) Scab Red, then highlighted first with Red Gore, then Blood Red, and finally Fiery Orange as a fine highlight.
His jacket is Blazing Orange highlighted through to Sunburst Yellow, then Skull White added for the final highlights. The design on his jacket is Chaos Black mixed with Blood Red, with a couple of highlights done by adding more Blood Red.
The skin is painted in dark red/brown tones. First with a basecoat of Dark Flesh.
Highlighting with Vermin Brown, then adding Dwarf Flesh for successive layers.
The lightest highlight is Dwarf Flesh by itself. After the skin was complete, I painted the eyes with Red Gore, Blood Red, and finally a teensy dot of Skull White to bring them to life. I painted the palm of this wizard's outstretched hand in the same colours as the flame, to give more of an impression of him casting the spell.