Possible Duplicate:
How do I find out the additional 3 effects of ingredients?
In an answer to this question, Fabian mentions that you can discover new potions by trying out different kinds of ingredients that match together.
Are there any other ways to learn about new potions?
In the alchemy tree, the Experimenter perk allows you to learn more of an ingredient's effects. Investing 3 skill perks in this perk, allows you to learn all 4 in a single tasing. Once you know the effects of each ingredient, you mix and match the ingredients for your desired potion/poison effect.
You can also find recipes, for example I lifted a couple of new recipes from the alchemists in Rifton.
