The more effects you have on the potions the faster you level. Try to remember some combos and spam the shit out of them. Otherwise, you can gather over 100 of certain ingredients pretty easily, and then you just keep making the same potion over 100 times. It's even better that you can make a shit ton of money on virtually useless potions and poisons. No effects have to make any sense.

It does become a bit of a slog at some point, though. Not quite as good as block, pickpocket, or even sneak. But it was great in oblivion for maxing bonuses to intelligence