I don't have a background in art and I am by no means an expert!
When I first started quilting more than 20 years ago, I played safe, I chose either a print fabric and then pulled colours from that print or I bought a collection of fabrics e.g. a fat quarter bundle. There is nothing wrong with this but I realised early on that I was drawn to scrap quilts, I love them 😀 the more fabrics the better! Why use one green fabric when you can use 30 😀 The problem with scrap quilts, is that if you are not careful they can end up looking like a bit of dog's dinner. The way I try and avoid this is to limit the number of colours in the quilt, not the number of fabrics.
One of the best things I have bought is a colour swatch guide, this one is by Joen Wolfrom, it really helps me to identify colours in fabrics
When I start a new project, I normally have an idea of the sort of look I want, I can get colour inspiration from almost anywhere: magazines, paintings, postcards, photos or from fabrics and other quilters.
For my next project I have started with a piece of fabric I love - this may or may not make it into the final quilt but it is my starting point. (This is a Liberty Tana Lawn 'Small Susanna')
I go through my stash and pull any fabrics in these colours, adding in some ivory as a neutral
The blue is wrong, it took me a while to work out why, but I have pulled Cerulean blue. I don't have any Turquoise in my stash, I could go and buy some, but I do have some lovely Aqua Greens, so I start again with those
I like the pinks, oranges etc in the original fabric, so again I check the colour wheel and see that Aqua green sits opposite Red, I then look at the colours either side of Red and decide to chose from Fuchsia through to Golden Yellow, with my complementary Aqua Green
I go back to my stash and pull anything that might work
I leave the piles of fabric where I can see them and look at them each time I am passing, adding or subtracting any that stand out. I find it really helps, if I start by thinking about what I don't want, this quilt is to be quite bright with clear colours, so I pull out all the fabrics with a Grey muted feel. I also decided I want colour to do the work not value, so I pulled all the very lights too. I will add contrast with a fresh ivory instead. The pattern I am thinking of making is very intricate with small pieces, so again I decided to eliminate large prints/patterns and will work just with solids or tone on tone fabrics.
This is not the final selection, I need to buy some more fuchsia/magenta and maybe a couple more golden yellow/oranges to give enough variety, but it is a starting point and these colours will give me the look I was after.
I hope that has been helpful, colour is a very personal thing and what looks good to one person can look hideous to another. If it looks good to you then it is right and don't let anyone tell you that your colours are wrong 😀