I have a cool toned complexion and ash blonde-turning grey hair. I wear cool toned clothing exclusively -- soft white, grey, charcoal, taupe, denim blues, ink, and navy are my neutrals. My colours are different blues, raspberry, cranberry red, fuchsia, teal, plums, orchids, and black. (Yup. Black functions more like an accent colour than a neutral in my palette.)
But here's the thing. I have a pair of cognac sandals that I love. What do I wear them with? My denim blues, whites, grey, ink, navy, black. Fabulous pairing!!! The cognac adds some interest to the cool tones and spices them up.
Most of my other footwear is on the cool side, but another favourite is a pair of leopard print slip on sneakers. Again, they look great with the above neutrals.
When it comes to metals, I also mix. My wedding band is silver and rose gold. I wear gold gold also sometimes, though my fallback is silver toned jewellery.
If an article of clothing or a bag has obvious hardware I usually try to match it with my jewellery. But if it's in an unnoticeable place (like a shoe buckle at the back of the heel) I don't worry about it a bit.