when using only VGC paints one of the best ways I found is using a 'gold' that you like (polished/glorious/dwarf bronze (or something similar)). I'd take the glorious one.
Shade it with normal colors to match a feeling you'd like (traditional: browns, cold/noble feel: purples and blues, etc.), I really like the extra colors the following bring to shading gold: darkflesh, imperial purple, nightblue, dark-green-ink.
The tricky part is highlighting it, for that I'd simply mix Vallejo-metal-medium to the chosen gold and go as high as you like (up to almost pure medium)
Another way (I like this one much more, as for me shading is easier than highlighting, no idea why): Get VAC-Gold. It's a really-really light gold, then shade the hell out of it with the colors mentioned earlier or with different inks.
It helps a lot if you do a little sideproject just to practice working with metallics. Here is one I did in 2009 (first serious try at using a metallic color and a lot of glazes):
https://picasaweb.google.com/104987920342761668493/Festesek#5463768367727139442
Except for the base-eyes and plasmapistol every part is made with metallics. The effect is really visible on the 3rd part of the pic (rest is too dark).
What I tried here:
- base with a bronz colour (dwarf bronze),
- shade with: VMC RedTransparent, VMC Violet, VMC Blue Transparent in this order
- retouch in a few places with the base+metallic medium
After being finished with the excercise I gave it away to a friend.
as a side note: you can make really convincing looking golds when mixing for example mithril silver with yellow and red inks or even mixing it with a brown (snakebite, bestial turn out to be good)