Well - as you mentioned trying to highlight black here are a few tips which you may or may not want to try:
1> Don\'t use black as the base colour - use a very, very dark grey - then you can still highlight and shade normally
2> If you are dry brushing your highlights, get the brush almost completely clear of paint and do loads of layers - if you can SEE the effect aftre the first two brushes you have too muh paint!
3> If after all your highlighting you feel you\'ve gone too far, wash over with thin black wash - this will not completely remove the highlights, but tone them down.
4> Try using different colours other than simply codex grey/white - try blues, purples, greens and browns
1> Don\'t use black as the base colour - use a very, very dark grey - then you can still highlight and shade normally
2> If you are dry brushing your highlights, get the brush almost completely clear of paint and do loads of layers - if you can SEE the effect aftre the first two brushes you have too muh paint!
3> If after all your highlighting you feel you\'ve gone too far, wash over with thin black wash - this will not completely remove the highlights, but tone them down.
4> Try using different colours other than simply codex grey/white - try blues, purples, greens and browns