People tell me all the time that they're not sure how to mix and match colours. And it's true, there is a whole science behind it (and it helps to understand colour properties, and terminology which I've written about here), but if you don't want to even have to think about the theory, why not just take a multi-coloured patterned garment or a scarf as your inspiration for your outfit's colour scheme.
Here I've used this shrug (which I knitted - pattern here) that has tones of grey, greige, white, baby pink and orange (now there is an example of a warm colour being thrown into a cool pattern, but because it's only a small proportion (less than 10% of the total) it still makes the pattern read as cool).
From this I then paired the mushroom boots and top, the grey skirt and pink scarf to create my outfit for the day.
This outfit's colour scheme was inspired by my scarf. It has shades of soft light blue, green, pink and violet so I used the green and pink and went for a softer lighter denim rather than dark denim to create a more harmonious outfit. Notice how I've toned my shoes to Cleo (my whippet)? Completely on purpose of course!
This scarf has a dominant teal, but touches of yellow, purple and warm red-violet. So I took the red-violet for my top and then the deeper purple for my earrings and bracelet.
If you want inspiration for a whole capsule, watch the video on how I pack 72 outfits into carry on luggage where I use a patterned skirt as the inspiration for my capsule.
I've also created other capsules around a patterned garment to give you some more inspiration.
You may also find this post on what are clashing colours useful too to help you with your mixing and matching.
Plus here are 7 colour schemes to steal if you don' t have a pattern you want to copy.