I've found the GW washes invaluable in my painting - the trick to effective highlighting is effective shading. If you can drag your shadows down deeper, it makes your highlights pop higher.
For red, I'll use one of three washes : Devlyn Mud if I want a dirty looking red, Baal Red if I want a rich looking red, or Leviathan Purple if I want a regal looking red. One way or another, the combo is usually to paint the base shade of red, wash it with one of the above washes, and then hit it with glazes of my base red again. If I need higher highlights than that, I've got a red-orange that I'll water down quite a bit and glaze that on until I've highlighted it to where I need it.