1. No looking up things on the internet - never had a problem with this anyway.
2. Don't use fast travel to get to major cities if, like in Oblivion, they are marked on the map from the get-go (travel there at least once by foot). Again, didn't have a problem with this.
3. Don't abuse the leveling system until the main quest is finished (provided it will be abuseable at all in Skyrim). After that I don't give a hooey.
4. No trainers - use the time to explore dungeons instead, and save on cash as well.
5. Forget I know anything of the existance of level-scaling or dungeon level-locks, and play as if I was completely oblivious to those mechanics.
6. Stick to my character's back-story (imitate his attitude).
7. No mods on the first playthrough
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8. If the quest giver says "You have to hurry! There's not much time left!" I don't pretend that I don't give a #@$% and go about doing ten other things before attending to the quest. I drop everything else and do it.
9. If it turns out that some skills/perks are overpowered or underpowered, I ignore it, and stick to the character build I had in mind at the start.
10. If a guild is obviously irreconcileable with any that I already belong to, I don't join it just to see if I can complete every single quest in one playthrough. I stay loyal. That pretty much means no Thieves Guild or Dark Brotherhood (Fighter's and Mage's Guilds instead).
...that's it. Ten's a good number
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