If I were you, (giving that you are going for the PS type colour that you posted) would take the following steps:
Wash with devlan mud and gryphone sepia into all the panel lines (no water needed)
Re-spray with a slightly lighter version of the base coat
Panel line edge with more bleached bone into the base mix
Final edges/ points with a bit of white in the mix
If you can also- try and spray from above, down, this will give it a slightly 'zenithal' highlight;-)
Now hurray up and send me my suits!
cheers
WARHOUND