What I've been doing for the past several weeks is refining my tactics and strategies to lead up to this very event.
One hard and solid rule I have is to use no kind of console command, or any other "INSTANT" change to the game in order to bring this off. I insist on using only what is in the unadvlterated game, plus the Official DLC's like the Dawnguard and Legendary ones.
The Legendary DLC is vital, in fact. Without it you can't roll-over skills and reclaim the percs from them.
I also began to move up the difficulty level as I went along after an experiment I did not long ago wherein I fiddled with the difficulty in order to capture the Aetherium Crown - this game has been at "Legendary" ever since the escape from Helgen Keep. I have kept the difficulty all the way up no matter what - again, that challenge thing.
I've had several chars above 400, and the whole thing began months ago when I read a post somewhere online about how someone had gotten up to level 256, and that it took them MONTHS of gameplay to do it...
I've had the game now for around two years. I took half a year off to dive into Oblivion when I heard it was a bigger game in terms of questlines, even though the graphics are not hi-def like Skyrim. Doing that gave me a few more ideas, and after a while I kept having ideas chase themselves around and around as I was playing.
~These games ARE really great for giving your subconscious mind a chance to chew on things.
By "Anything Goes" above, I mean literally any kind of exploit you can think of - although I avoid the famous Fortify Restoration gambit because it made my game freeze when I ran it up too far. I don't think much of the Ogma Infinium exploit either, you can tell it isn't supposed to happen in the game - they never intended for the book to be re-usable.
But using Ralof as a practice target in the Helgen tunnels - also using the Bear you find in there to run up restoration and whatever armor you chose (you have to be sure Ralof exits the tunnels ahead of you, and then go back). Putting a rubber band around my XBOX controller to accomplish "AUTOMATED" levelling tactics, like setting my guy to sneak in a circle while I go wash some dishes or whatever... That's a mechanical exploit, and is acceptable to me because I could just as well hold the joysticks myself and do the same thing. The rubber band is mainly used to hold down the left or right trigger for various purposes.
Any of us can also take advantage of the Alteration skill to make fast levels at any point - I just anolysed it and worked out a way to get absolutely crazy levels out of the TK spell. It calls for high levels of enchanting, and alchemy to set up some accessories that fortify alteration and magicka regeneration. That exploit right there is key to the radically high levels I am going to run this game up to.
The player char is named Bloody Roger, if that makes any difference.
Getting all three homesteads and setting up the gardens and greenhouses for an endless supply of alchemy ingredients is another helpful key.
Installing an alchemy bench and enchanting bench IN THE MAIN HALL, in every one of them - you don't need an enchanters or alchemists TOWER, the greenhouse is more important, and I like having lots of storage.
I am pouring everything I have come up with about SKYRIM over the last two years all into this single game, and doing it BEFORE ANY OF THE MAJOR QUESTS are launched.
That has changed the entire game right there. It makes the "Training Phase" a complete gaming experience all by itself.