As I proceed in painting more and more blood angels (im now addicted to this painting scheme), I realized that GW actually makes decals to support this first founding chapter (unlike my Raven Guard... though forge world did just release a Raven Guard Dreadnought). After toying with the GW decals on a model or two, I realized that these decals are way to thick when applying to anything other than a flat surface. One example, when I initially applied the BA icon to the shoulder pad above, it looked awful, not conforming to the rounded surface at all. So, with a little trip to the local hobby shop, I found "Decal Medium" (aka decal thinner).
What I ended up doing was applying the decal as normal (with warm water/vinegar mixture) and letting it set for just a moment, as I dabbed away the water both atop and beneath the decal as I pressed it down (be careful not to shift the decal however). After removing excess water off the decal, I used an old brush to generously apply 2 coats the decal medium (both atop and beneath the decal). Let it set for at least 8 hours, as by then it should have formed to the curved surface of the model. After letting it set, the decals look fantastic. Be sure to trim the decal as close to the icon as possible, as so you dont get excessive shine from the decal surface on the model. I always, always recommend you to grab your thinnest brush and apply a little paint to the decal, using it as a guide (ex. the yellow blood angel drip - apply a little yellow paint to the inside of the droplet, it makes it look less like a decal and takes away the shine).
Here is the chapter thus far:
The red helmets look better in my opinion, but im working on getting the yellow helmets to look as good (yellow is a pain to paint with).