I know that lots of people shy away from busy colorful patterns. I'm drawn to them. As a graphic artist I am keen on discovering new interesting patterns to inspire me. I also know that great patterns can be wonderful additions to any wardrobe.
When choosing patterns look at the colors. If there are many colors in the piece like this blouse you are guaranteed to find something in your closet that will work with it.
Be aware of the size of the pattern. The bigger the pattern normally the bigger you need to be to wear it.
If you need to hide certain areas of your body busy patterns confuse the eye and camouflage unwanted bumps or bulges.
Patterns can be challenging to mix with other patterns. Generally you want to keep each pattern a different size so you don't wind up looking like a sale bin at a fabric store. Make sure at least one color is common to each pattern. A good way of understanding patterns is by flipping thru any interior design magazine. They often have rooms decorated in stripes, patterns and solids which coordinate into a lovely room. These same techniques can be applied to dressing yourself keeping in mind that you are not as big as a room, so you should streamline the concept to your size.
Here I have chosen to mix the one colorful pattern with a bunch of solids. The bottom half is a bit of color blocking thanks to the purple tights.