A painting conundrum - highlighting black

Hellooo Lustrians,

Once again I've flip-flopped on the theme of my Lizardmen. Originally they were Chaos Tainted, but that ended up going in the too hard/too expensive basket. Then they were Khemri themed but that went out the window when the new TG kits came out and I fell back in love with the Aztec/Mayan feel. Then they were black and red, but they looked a bit rubbish and someone else on this forum done the same colours way way better than I could possibly imagine (also I'm goddamn sick of painting red. Stupid Word Bearers...).

Now I'm thinking of changing from a yellow/orange Hexoatl army with lots of fire themed stuff to a black/purple Death themed army. This is in no small part due to the release of the Nagash book, but also due to an awesome death/necromancy Slann and skink priest conversions I have in mind.

My problem? How on earth do I highlight black!?

To put it in perspective, my painting skills are pretty much limited to drybrushing, dips and washes and the last time I tried black as my primary colour (see the red/black theme above) they ended up looking blue-grey rather than black with highlights.

Does anyone have any hints, ticks or know of any simple walkthroughs I could refer to?

Thanks in advance!

http://blog.brushthralls.com/?page_id=1942
http://flameonminiatures.blogspot.com/2014/01/black-color-painting-tutorial.html
http://miniaturemiscellany.wordpress.com/tutorials/painting-black/
http://www.how-to-paint-miniatures.com/miniature_painting_armor.html

When highlighting black I just use the mechanicus standard grey from GW. It highlights black pretty well without being too extreme. If you wanna shine the money pick a lighter grey for the highlights of the highlights! Also you can always wash the highlights abit if they get too bright.

When highlighting i generally use a normal brush if the smaller range when highlighting. I also make sure to have enough water in the paint so that the highlight doesn't look too dry. The only time I use dry paint/drybrushing for highlights is for stones and sometimes scales. But then again I don't use drybrushing that much overall so i might be biased into not drybrushing highlights...

On a side note, I once used a dark blue for highlighting black when painting some 40k back in the day. It turned out pretty well then but I'm not sure it'd fit on lizards.

Hope this helps!