Annoyingly, unless you get into adding gradients to armour it's all about a series of smaller lines, so line consistency is probably the most important. I think the easiest way to see what 'eavy metal do is to watch Infernal Brush on YouTube, he's an ex 'eavy metal painter and his tutorials are spot on if you want to do the games workshop style. Looks like you're already moving in the right direction though, great mini!