Simple Stuff:
Shock Shield: Corn + Daedra Heart. If you're a spellcaster, don't substitute Rice for Corn; you'll get a Silence side effect, and Mages don't need that static. If you're a warrior who happens to be big on Alchemy, however, go right ahead. Mix all the rice and daedra hearts you want.
Chameleon: [Columbine Root Pulp / St. John's Wort Nectar] + [Bloodgrass / Daedra Silk / Radish]. You can also combine the ingredients in that first bracket with no side effects. But if you combine Bloodgrass, Daedra Silk and/or Radish, you tend to get a little Burden with your Chameleon, which sucks. Venison also has Chameleon properties, but I feel that it's better used in Feather and Restore Health potions. (Remember: Drink three or four Chameleon potions and you've effectively cast an unbreakable form of Invisibility on yourself, so you can run around stabbing daedra rampantly without getting your butt spanked.)
Shield: [Potato / Flax Seeds / Tomato] + [Bog Beacon Asco Cap / Cinnabar Polypore Red Cap / Emetic Russula Cap]. Don't bother combining Bog Beacon Asco Cap and/or Cinnabar Polypore Red Cap and/or Emetic Russula Cap; you'll get a heap of side effects. Especially with the Bog Beacon and the Emetic Russula. Why Bethesda saw fit to give us two different ingredients with the exact same four effects is beyond me.
Light: Mix any two: Alkanet Flower, Daedroth Teeth, Glow Dust, Milk Thistle Seeds, Watermelon, White Seed Pod. (Exceptions: Daedroth Teeth + Watermelon also hits you with Burden, and Glow Dust + Watermelon also hits you with Damage Health. Damn that Watermelon.)
Night-Eye: Combine any two: Bonemeal, Carrot, Daedra Silk, Daedroth Teeth, Lady's Mantle Leaves, Viper's Bugloss Leaves, Worm's Head Cap (SE). (Exception: Don't mix Daedra Silk, Daedroth Teeth and/or Viper's Bugloss Leaves or you'll get Burdened.) Night-Eye potions don't last nearly as long as Light potions, but Light potions tend to give your position away when you're sneaking around. If you want to see in the dark without forfeiting your chances of stabbing bandits in the back, go with Night-Eye.
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Simple Stuff, if You're a Master of Alchemy:
Chameleon: Bloodgrass. That's it. A casual stroll through Oblivion can net you buttloads of Bloodgrass, and it's the only plant in Oblivion that doesn't try to kick your ass. Load up on Bloodgrass and go nuts with the Chameleon potions.
Restore Magicka: Bog Beacon Asco Cap, Flax Seeds, Steel-Blue Entoloma Cap or Void Salts.
Restore Health: Cairn Bolete Cap, Daedra Heart, Lady's Mantle Leaves, Mugwort Seeds, Venison or Ambrosia (SE).
Fortify Health: Mutton or Unicorn Horn. Unicorn Horn is pretty rare, so I'd rather use it in a potion with multiple effects, like Health Surge back there. But that's just me.
Damage Health: Harrada, Nightshade, Spiddal Stick or Wisp Stalk Caps.
Light: Milk Thistle Seeds.
Night-Eye: Daedroth Teeth.
Detect Life: S'jirra's Famous Potato Bread. That quest only gives you five loaves of potato bread, so make 'em count.
Restore Fatigue: Okay, here's what you do. You walk into the nearest tavern or food store. You talk to the merchant or bartender, and you see what he or she is selling. Every ingredient sold at taverns or restaurants has Restore Fatigue as its first property, I swear! My Dunmer Mage has little use for Restore Fatigue herself, though. Why run around swinging at things when you can just throw up gang signs and burn people alive? Mages rule! >:)
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Simple Stuff, if You're a Master of Alchemy, but You Might as Well Not Bother because Turning Them into Potions Won't Make the Effects Any Better:
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Cure Disease: Mandrake Root, Root Pulp or Shepherd's Pie. Remember: Get a lot of money, buy Rosethorn Hall in Skingrad, go around the corner to Colovian Traders, buy every last upgrade you can get for that house, then give Eyja 150 Septims to be your maid. Then go back to Rosethorn Hall and ask Eyja for Food over and over. BOOM! Free all-you-can-eat Shepherd's Pies. :)
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Simple Stuff, if You're a Master of Alchemy, but Go Ahead and Turn Them into Potions because Even Though You Won't Improve the Effect, the Damned Things Weigh Two Pounds and Turning Them into Potions Might Make Them Significantly Lighter:
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Cure Disease: Clannfear Claws. TSIA. Besides, would you want to stand there gnawing on some demonic velociraptor's entire hand? Do your character a favor and turn the Clannfear Claws into not-so-gross Cure Disease potions already!
(Or mix in some Daedra Venin and turn your Clannfear Claws into those Crippler potions back there. Either or.)