One of the questions I am frequently asked is how do I pick fabrics to go together in a project. The honest is answer is...I go for both the obvious and also the not so obvious.
Meaning, it's easy to mix and match when you pull from the same fabric line that was designed to go together. BUT you can also look at just one color in a particular print and find it on other fabrics that will make a surprising coordinating look. THIS is a pretty good intro into color theory and the color wheel that you might want to read and bookmark.
Jennifer Paganelli is the queen of that surprising coordinated look - she pairs colors that you might not think to put together, uses richly sophisticated prints and what you get is this classic look with a really modern spin to it. She's one of my favorite designers, can you tell?
Jennifers Sis Boom collection of fabrics are really fun and she recently came out with this new book called Girls World and my, oh, my! Lots of great projects, very easy ranging to a few that are a bit more complicated - all very well done and this book will give you a TON of color inspiration. So, if you ever wondered how to mix and match fabrics - you will enjoy seeing how Jennifer does it and does it so well. Quite frankly, it just looks pretty sitting on my shelf in my sewing room. If I could wrap myself completely in the pages of this book - I would. I love it that much. Who would not want a room full of all that whimsy and color?!
I was really inspired by Jennifer and dresses like the one above from her book when I was planning my Easter dresses this year. I made all three of my girls, my two peas and my sprout, dresses with some Sis Boom prints. I must get a better picture I can share - but this one shows Sprout in her dress (who also was celebrating her birthday that day!) and you can barely see the peas dresses to the left and right. That's kinda how they always are...hovering over Sprout. 
When mix and matching prints, I've also noticed that you can often find one color in a line of fabric and that exact color in another line by another designer. A few lines ago, I found a pretty olive green in some Amy Butler prints that went well with some Heather Bailey prints and much later, some scraps of those that go well with some Riley Blake prints. Really look at each and every color in a print. You will be amazed at how often you will see it repeated elsewhere. That makes coordinating prints easy.
For me, I usually start with a main print, something I really love...and I will head off to the local quilt shop and pull bolt upon bolt down and lay it with that main print. Sometimes it takes while to for something to click but you'll eventually come across something that just seems to be a great fit. Plus, that gives you a chance to feel the fabric too.
If that isn't an option for you, I love the design board that Quilthome.com has on their website. You can drag prints around the screen to see how they look together. Do you know of other sites that offer that function? Share in the comments!
Do you have any tricks or tips for how you match up fabric prints together? I think it really comes down to what you love...and if YOU love the way it looks, then success!