For me, my toughest skills to level up were Restoration and Alchemy. Before I got better Ward spells and turn undead, I could only level up restoration by healing damage, and as a squishy mage I tended to stay away from damage whenever possible. Even after getting wards and turn undead (both of which I used a lot) it still seemed to take forever to level up Restoration.
Alchemy takes me forever to level up, because potions/poisons with only one effect seem to not count much at all toward skill progression. Sometimes I get lucky and have some ingredients that just happen to make really complex potions that contribute more to level up. But still, it's taking a lot longer to level up alchemy without paying for training than it does to level up, say, Enchanting or Lockpicking. I'm not even a thief, but my lockpicking is at 80 just from opening the various locked doors and chests found inside dungeons. Yet it seems like I have to brew dozens of potions to level up my alchemy skill.


