When you are mixing patterns, there are a couple of things you need to consider: size and color.
You want to match your patterns by size - small pattern paired with another small pattern or large pattern with another large pattern. Mixing two different sizes can be a bit challenging, and if you are going to mix sizes, I would suggest going with one size for your outfit and another size for your accessories, rather than mixing sizes within your clothes.
Combining patterns in neutral colors is quite easy. Traditional neutrals are black, navy, brown, and white. More advanced neutrals can include purple, leopard, and polka dot. The more advanced neutrals are so versatile, because they can go with warm or cool colors.
The reason that the outfit from my "CPTS" post worked so well is because the patterns are both small (tiny polka dots in the skirt and thin stripes in the shirt), and they are both neutrals (black, white, and gray).
This outfit works for the same reasons, neutral colors and small patterns. There are the tiny polka dots in the cuff of the blazer, a thin lined chevron in the t-shirt, and snakeskin in the flats. (All of the photography below is credited to the wonderfully talented, Nathan Knauss! Thanks for working with me, Nater!)
Another option to introduce yourself to combining patterns is start with a patterned piece that is all the same color, like this white eyelet skirt. I paired the skirt with a bright yellow checkered plaid shirt. The skirt acts like a neutral bottom, just like a plain white skirt would, but it adds so much more interest to the outfit, because of its pattern (and texture!).
And now for the fun and adventurous! In this outfit, I mixed three patterns! Crazy, I know, but it works so well, I would be crazy not to do it! The reason that this works is because I started with a somewhat bold, all over print with the dress. (I love that lace is so in right now.) I added a bold statement necklace that has pattern within each stone, and finished this look with brown and black snakeskin pumps. The accessories work as well as they do, because they are all made up of neutrals! The stones in the necklace have cream and black, the pattern of the snakeskin is brown, black, and white, so neither of those two patterns take away from the beauty of the bold dress.
With all of the outfits pictured in this post, you could absolutely swap out one of the patterned pieces for a solid. That wouldn't be wrong, and I am sure that we could make it look fabulous. You can even tone down a patterned piece by breaking it up with a solid, like throwing on a jacket
However, when you mix patterns, and you do it well, it elevates your outfit and your personal style.