I love mixing patterns. Let me clarify - I love mixing some patterns with other patterns, as long as the size of the pattern is proportional and the colours are contrasting. Don't get me wrong - I'm not a fan of the "overly mixed combination of patterns as often seen in Etro campaigns" ...nothing against Etro. I do love their shirts and incorporation of whimsical fabrics in unexpected places.
So, when you're ready to step up your A game and truly Mix and Match, think about these suggestions:
If one pattern is small, another must be large. For instance, I have a pink and white gingham button down shirt, with a pattern that's fairly small. With it, I'll pair a silk scarf that's grass green with TINY white dots. Or sometimes with the same shirt, I'll wear a tie of the same colours, but featured in an oversize paisley pattern. The contrast of the giant paisley against the small gingham is definitely pleasing.
When you incorporate multiple patterns, you really can Mix and Match!