Step 1: Undercoat - Mournfang Brown (gold coats better with brown underneath, this is a very warm brown, that'll show through in the gold a little).
Step 2: Bascoat - Vallejo Old Gold, mix in a tad of Mournfang Brown, two thin coats should do it, one if you're airbrushing.
Step 3: Wash - Seraphim Sepia, two coats, let it dry between each (AP Soft Tone Ink may be better, see bottom of post).
1st coat:
2nd:
Once Dry: (you could leave it here if you're going for speed)
Step 4: Highlight - Light Drybrush with Shining Silver
Step 5: (optional) Detailing wash - carefully wash the recesses again with a light touch of Sepia.
Done
Ramblings/alternatives
I've used the new GW washes here, which in general I am not a massive fan of, they can be excessively gloss, and if used any other way than in a few thin coats don't seem to pool as nicely as the old ones. So bear in mind that (for a change ^_^) a few thin coats will probably work better.
Their slight gloss finish isn't an issue for me with metallics, and the drybrush highlight goes a long way to counter their drawbacks, however if you're after something less fussy, my beloved Soft Tone Ink may be an easier alternative, and in retrospect this is what I'd use in general.
If you want a SUPER YELLOW gold the GW Lamenters Yellow Glaze is a good bet, thin it about 1:1 with water an do a super light coat all over, this'll act like a filter and make things very warm in tone.
If you want more contrast adding a little purple wash to the recesses works beautifully, if you want it really strong go purple+black (Army Painter Dark Tone Ink), but I'd stay away from straight black personally, unless you're looking to blackline.