In these two examples, I have mixed prints but have stayed within the same color family. In other words, the floral shirt/shoes and plaid jacket are different prints but they use many of the same colors. This makes print mixing more "safe" and many women feel better combining the patterns when they keep the prints in the same color realm. The other outfit has a different print for top and bottom, but both are the same colors. The pop of red and leopard in the handbag and shoes gives the outfit a nice punch.
As a general rule of thumb, I suggest not going too crazy with accessories if you choose to mix two different prints. In the examples above, the jewelry, while staying in the same color scheme, is simple and not too flashy. This allows the focus to remain on the outfit. Even celebrities embrace the dual print ensemble. Here are some Hollywood fashionistas sporting the mixed print look and as you can see, the focus is on their outfits and not their accessories. These are great examples of how to wear mixed prints well.