Thanks guys for all the comments...
Yes, well my favorite technique is the three stage process. I use acrylic paints so.......
1st primer coat
2nd preshade flat black
3rd postshade with Tamiya smoke with a 70 - 30 mix (Tamiya thinners)
and for a final touch ill use Phil Flory's promodellers wash black witch by the way is a clay base wash and comes off with just a damp paper towel to desired effect.
thanks again...