I've actually found yellow and red colors to be troublesome, but I haven't had that experience with other light colors- especially ones that are a little de-saturated (like light greys, blues and such).
The first think you should do is make sure your paint is well mixed. Stick a toothpick or the back end of a brush in there and stir it up some.
If you want a good strong bright red, there are a number or ways to produce this on your mini.
The first way you can do over either a white or black undercoat, but I would prefer black. Mix your color with some white (a non GW acrylic white will do well, I recommend Dealta Ceramacoat from Micheal's or Robert's). You'll have a horrid pink color that you can put onto the mini on all of the areas you want to be bright red.
He will look pink and horrid.
After that, go over all of those areas again with your blood red paint. This time, the almost translucent paint will have a better time creating the bright red effect you are looking for.
By the way, P3 paints tend to coat better (metallics being the exception). P3 Khador Red Base still has a harder time coating than darker colors, but it coats quite a bit better than Citadel Blood Red.