For blood (on my ogres), I used to use a great mix of red ink and gloss varnish. Sadly, they don't make red ink any more and the current wash isn't red enough. I suppose you could try with another company's red ink, or really watered down blood red. This mixture was pretty good, because I could trickle it down models to make it look like they were actually bleeding. However, this would probably be a bit hard on space marines as they are small.
But try blood red and gloss varnish (maybe with a bit of red gore or something to make it less bright. This was easier with red ink). Don't put too much on. Here's something that I did with only blood red and gloss.