I am definitely not the best at mixing patterns. So, I won't give you tips.
However, I made a press review of the best posts on mixing patterns.
I'm sure you'll find some usefull tips!
Credit : Barbara Barry Boutique on Etsy
Apartment Therapy :
Credit : Anna Spiro
Centsational Girl :
Naomi Stein House
Credit : Design Sponge
Emily Henderson :
Little Green Notebook :