HI Ashley, I'm no expert but I have thoughts on the subject! I have three holes in each ear. Just regular piercings and I usually wear white gold studs in the top two, and change the original piercing regularly, often with dangling silver earrings. That's sort of my regular look. I have been thinking about the mismatched look lately and considering giving it a try. I think I will do it in the original two holes, the ones where I usually change my earrings, and continue to leave the other holes filled with the small studs. I'm kind of lazy so that seems like the best idea to me.
I am going to try some mismatched studs, having bought some inexpensive ones recently, and am also going to try a small hoop in one ear and a stud in the other. I think you should just experiment and find a look you like. Some people even wear a big and bold earring in one ear and a small stud in the other. Pulling it off just takes confidence. Act like it's intentional and you've pulled it off!
