There are two different ways that I would attempt it:
1) Paint all the gilded armour in your gold colour first, add highlights where such would appear, but exaggerate them strongly. After this is dry, paint black over, leaving thin lines where the the gilded lines would be. Over this black, work up your metallics while leaving a tiny sliver of a black line bordering the gilded line.
Advantages: far easier to highlight the gilding lines, and often it\'s easier to create a pattern by blacking in an outline than it is to paint the pattern freehand.
Disadvantages: you REALLY need to have the pattern planned out exactly as any mistake with the black lining would be much harder to correct, and you obviously won\'t be able to drybrush the metallics.
2) Paint the armour as normal. With a very fine brush, add your gilding pattern in black, then put gold/silver over this, then highlight the gilding.
Advantages: A lot more intuitive method of doing it, and mistakes would be easier to correct.
Disadvantages: Often it\'s harder to free hand a complex pattern as opposed to just blocking in the borders to the pattern, and highlighting the tiny gilding lines properly will be a much larger challenge.
In both cases, you\'re going to have to rely on a brush with a very fine tip and appropriately bright shade of gold or silver for the gilding (such as Vallejo\'s Metallic Medium, which is practically metallic white). Also, I think the key to making this sort of thing work at the 25-28mm scale is using black (or a dark brown, dark grey) to define the gilding -- anything as subtle as what\'s in that first linked photo is simply going to be easily overlooked without some exaggeration.
The Inquisitor there looks a lot more like tactic two to me, and the gilding obviously isn\'t that fine -- it\'s just a few well-placed freehand lines, really.
Hope that bit of rambling helps!
Kep
