Mixing prints can be fun or a headache! For the novice, try a classic mix of polka dots with stripes. If you are no novice, then try a floral print with paisley or multi-print. Just have fun with it! It will be easier than you think.
Here are few examples, mostly from Anthropologie...they always have great prints every season.
All The Wharf Cardigan by Anthropologie
Take Action Dress by Girls of Savoy
First Hints Blouse by Lil
Caramel Patterned Silk Skirt by Etro
Geo Feather Blouse by Fei
Ackee Pencil Skirt by Corey Lynn Calter
Slice of Life Tank by Porridge
Las Ramblas Shorts by Habitual
And I'm off and running...