Join Date: Mar 2008
Location: Rochester, Medway, Kent.
I wouldn't say there are any real specific colours to avoid then, I'm not 100% behind the new GW paint line, but for a beginner they are fine. Purple can be a pain to get right but from how you've described the scheme it would look good with the green spot colour to off set it.
My best advice would be to stick to the GW system of base, layer, shade and highlight in the respective shades of purple (whatever they may be).
If you're mixing paints for highlights another good bit of advice is to avoid white, it reduces the saturation of the colour you're mixing it with. Go with an ivory colour instead, whatever the paint is that replaced Bleached Bone should be fine.
Sorry for the rambling response but I hope its of some help.