I normally do an undercoat, then basecoat, wash, layer, highlight or drybrush, then finally a glaze.
I use the highlight on the characters, drybrush on the rank and file for speed's sake.
I use the schemes found
here, using the second layer as a highlight.
They're pretty simple schemes to do, but look good when you pull them off, and it's got guides for Dark Angels on there. People seem to forget about this little gem of the
GW site.