Oblivion Power Leveling Guide: Alchemy Self Training
Attribute: Intelligence
Train acrobatics by eating ingredients and mixing potions. Keep in mind that while eating ingredients will increase your alchemy level, making potions will increase it 10 times faster. It doesn't matter what potions, ingredients or even how many ingredients you use. All potion making will increase your alchemy skill by the same amount. So go ahead and make 100 restore fatigue potions, it'll be just as useful as the uber-poison in leveling you up.
Alchemy is a great skill for two reasons: potions and poisons. Well before you get to the expert or master level, your potions will be much lighter than what you can buy, and many of them will work longer, better or both. Poisons are another lovely side benefit of the alchemy skill. Assassin characters should consider it for this benefit alone. Poisons can be added to any weapon and will affect your enemy on impact. When applied to bows, the poison will be applied to whatever arrow you shoot. Poison effects will stack with enchanted weapons.
As your alchemy skill increases, the number of effects you see will increase for each ingredient, allowing you to make more potions, or poisons, with fewer ingredients. Be aware that even with a high alchemy, heavy ingredients will always create heavier potions or poisons than their lighter counterparts. Also note that a stolen ingredient used to create a potion will not mark the potion or poison as stolen.
Extra Bonus
During the main quest you'll get a chance to rescue Jeelius in the Shrine of Dagon. When you see him on the alter, wake him before you take the book. Keep in mind that keeping him alive is quite the challenge, save the game before trying it since it may take several attempts. If he survives, he'll introduce himself outside the shrine, find him a few days later in the Imperial City in the Temple of the One. He'll give you a free boost to Alchemy, Mysticism and Restoration.
IMPORTANT NOTE: Don't eat poison apples, chokeberries or rat poison. Those are special items that will kill any character, including yours. They can't be used to make poisons either.