Well, I've got a little bit to say on hazard stripes:
I've got some Iron Warriors in the gallery too, I just went with one of my warjacks as the example.
Anyway, there are a few things that I think can help out.
First off- hazard stripes are a great place for weathering. A little battle damage will cover up any mistakes that you make. Blood Splatter can do the same job.
When you're highlighting, go up with both the black and yellow. If there'a hard edge, I usually make the hard edge highlight color the same for both the yellow and black (it helps homogenize the piece).
Otherwise, the pitfall I've seen people do is to make the stripes to thin. They need to be fairly broad- and based on the size and shape of the area they're on. So take a look at that when you're composing a mini, and remember that different areas don't need to all look the same.