I spent this weekend finishing off some Black Templars as part of one of my larger commissions I've got this summer. With two days of work, I was able to finish off 2 Attack bikes, 12 Initiates, 4 Neophytes and an Apothecary.
When it comes to putting decals that have white in them over a dark surface (black armour for example), I make sure I paint the area the decal is going to go over with a light grey or white. This way, the white portions of the decal stay bright.
And here's the rest of the troops...
This along with the Terminators I did the other day, gets me about half way through the project. Now it's onto some bikes, a Land Raider and some more troops for a DIY Space Marine Chapter.