When writing the appearance, I often start with height and weight, and let that flow into the characters frame, posture, body-type, bust, and build and get the general rough idea down. You spend a whole paragraph or two doing that. Then you get into the face on the next portion. 

Every face is different and unique, and has plenty of distinguishing features that sets them apart from others. The paleness or color of their skin, the sharpness of their features (cheek bones, nose bridge, brows, chin), complexion (acne, scars, freckles, blemishes, rashes or flushed skin), their eyes (shape, color, how the eyebrows work in unison with them to express particular emotions they most often show, depth [are they sunken or do they "pop" out]), hair (color, length, touch, consistency[silky, curly, rough, smooth, frizzy), and also the type of hair-line). The shape of the face is important, as are the ears they have, whether the ear lobes are attached or not. This is also a good place to mention facial piercings and other accessories.

The face usually takes one paragraph if you're snappy about it, two if you're getting flowery with your language. In all, you can get 3-5 paragraphs in your appearance section before getting to your clothes this way.