What is the shape of your face?
Oval shape ladies are in luck as almost any style of earrings will fit you well.
If your face is round, avoid repeating the same shape in your earrings, such as large round hoops or button earrings. Choose earrings that elongate your face, like a long dangle earring.
(Picture credits: I can't remember the names of these two ladies... can anyone help me?)
Ladies with a long, thin face would avoid long dangles and wear short, wide earrings, such as studs or chandelier earrings. Round, triangular or square earrings would work nicely to wide the shape of your face.
Long and/or round earrings flatter square shape faces. Oval (or any curve-shape) and hoops earrings help soften the shape of the face while long tear drop and multi-tiered dangling earrings add length.
If you are unsure about your face shape, hop over to The Beauty Department. They have a awesome pictorial decision tree that would help you figure it out.
What is the color of your skin and hair?
While there are no hard and fast rules here, ladies of warm skin tones (usually tan, olive or dark-skinned) better tend to look better in gold earrings, than pale, cool skin tones. The latter usually look gorgeous in silver earrings.
If you have dark, black hair, silver earrings would be fabulous on you. Blondes, on the other hand, tend to shine in polished or brushed gold. And copper goes naturally with red-heads.
Charlize Theron (source: Google Image)