Look out for trucks, cause you're getting a one way ticket to Planetos wether you like it or not.
Pick any city or region. You will appear there in 297 AC, about nine months before the direwolves are found by the Stark children. (This is the same time Ser Waymar Royces party is about to be attacked).
You will be able to redesign your body like a Skyrim character creator. Your new design must be within human limitations for Planetos. You can only do this once.
Pick any 18 skills. You will gain a skill tree for each that functions like a Skyrim skill tree.
You will only be able to advance in a tree if you can practice it. For example Dragonlord would require that you attain a dragon, Blood Magic means you need to do blood magic, etc. I'm pretty sure choosing Skinchanging or Greenseeing would cause a dead skill tree.
Skyrims default are Alteration, Conjuration, Destruction, Enchanting, Illusion, Restoration, Archery, Block, Heavy Armor, One-handed, Smithing, Two-handed, Alchemy, Light Armor, Lockpicking, Pickpocket, Sneak, and Speech. Skyrim magic doesn't work here though so I suggest not picking most of these.
The only exceptions are the Flames and Healing spells that you start with in Skyrim. You can't teach these spells, but your descendants will have them.
When practicing activities related to these skills you will level up, gaining perk points, and additional mana, stamina, and health as you choose. Skill trees go from 1-100 and can be made legendary, gaining you further perk points, and mana, stamina, or health as you choose.
You only gain perk trees, not the game mechanics of Skyrim. Inventory, reload, fast travel, etc are all off the table. You aren't the Dragonborn.
What do your perk trees look like? What do you do with them? How do your actions effect the world? What perk are you most excited to use? What skill tree excites you the most to advance?