After careful consideration, I have decided that these will be the 18 skills:
COMBAT: Block, Heavy Armor, Free Running, Smithing, One-Handed, Two-Handed
STEALTH: Lockpick, Alchemy, Light Armor, Speechcraft, Marksman, Sneak
MAGIC: Restoration, Alteration, Enchanting, Illusion, Conjuration, Destruction
COMBAT: Block, Heavy Armor, Free Running, Smithing, One-Handed, Two-Handed
STEALTH: Lockpick, Alchemy, Light Armor, Speechcraft, Marksman, Sneak
MAGIC: Restoration, Alteration, Enchanting, Illusion, Conjuration, Destruction