I was 70 when I started and wastly overpowered...
but I know some who have finished the main-game at level 1.
since all monsters and NPC scale with you.
so I wouldn't sweat it... start the quests you find and if you come against something you can't handle, then either flee or load the last save, go back to skyrim and level up some more.
the one thing you should *not* do is powerlevel the non-combat skills (alchemy, smithng, etc), as it will make enemies have level 30 (let's say) health, while you do level 10 damage.