The fastest way to look expensive is to use less color, more deliberately. One deep neutral, one warm accent, and a paper-like background will outperform a rainbow every time.
The 60-30-10 rule, refined
Reserve your accent for moments of decision: the primary button, the active link, the single line under a heading. When gold appears only where it matters, every appearance feels like an event.
Test your palette in grayscale first. If the hierarchy survives without color, the color becomes a luxury rather than a crutch — which is exactly what it should be.