I have made several primary skins. Most of the skins I've made go along the theme of a central character KnightMiner.
My first skin I call Matthias Knight. It is basically me as a knight. I first used this skin shortly after getting Minecraft, and recently started using it again with some of the new 1.8 features.
Matthias Knight has blue eyes and brown hair. He wears chain mail, a white tunic with a red cross, black pants, and brown boots.
Matthias Knight uses the second layer to add iron shoulder protection, a small shield, a sash, and golden knee protection.
CyberKnight is my second skin. I made some modifications to Matthias Knight, inspired by Docm77's skin.
CyberKnight wears a blue shirt with a white cross, black pants, and black boots.
CyberKnight has a second layer of a robotic eye piece, right arm cannon, left shoulder pad, and boots, which enhance his physical abilities.