I have beaten Oblivion, but I played it across two different gamertags on the 360.
So my achievements are all spread out.

I worked my way back through the mage's guild on a new character.
I have empty grand soul gems and a spell with chameleon.
My only problems now are that I still dont know what to kill to fill a grand soul gem,
2nd I am a vampire D:
I have no idea where to start the quest to get rid of the vampirism.

So, my problem isn't that I don't know how to do 100% chameleon,
it's just I've got some obstacles, please help.

Depends on your level, grand soul creatures, liches, minotaur lords, Xivilai, and the highest leveled goblin warlords and such do not spawn at lower levels, so you would be better off going the black soul gem route. Of course if you are level 10 or more, the ring of Kahjiiti really helps.
To start the vampire cure, go to the temple in the Imperial City temple district.

you can buy filled soul gems including grand but grand is leveled. also you can talk to the mage at the lobby of the mage university.

You'll need empty grand soul gems for the Vampirism cure, so maybe do that first and reconsider the chameleon after. I usually try and get Sigil Stones for part of the chameleon, after using Ring of Khajiiti, and any other pre-enchanted items I find, and then I usually only need a relatively minor soul gem for the remainder.

+1

I had 95% Chameleon by getting leveled Sigil Stones and using them to enchant armor. Add in a shield and amulet/ring or two and that had me up to 95%. Cast a basic 10% chameleon spell and it was over 100% for the duration of the spell.

It's a bit annoying, but there's a tendency in the game for particular enchantments to always be on the same type of item. In the case of Chameleon, there are a lot of Rings that give it, but you can only wear two at a time (without mods). You can also find it on a cuirass or two, but not boots, gauntlets, helms or greaves. I've often had two Cuirasses, a robe, and four rings all with chameleon, for a total of 180% and still needed to enchant another item, because I could only wear three of them.

Please note that a total chameleon enchantment over 100 give no extra benefit.

100% Chameleon requires at least 4 items, the most effective way to do this is with the Ring of the Kajiit, plus three clothing items with transcendant level Sigil Stone chameleon enchantments (see the http://www.uesp.net/wiki/Oblivion:Sigil_Stone article for info on getting the stone you want).
Remember that 100% chameleon, though useful at times, will get old andboring quickly if you use it all the time (think: taking candy from a baby, except that the baby is comatose). I'd suggest going for 90% or 95% chameleon (3 sigil stones, or 2 sigil stones+Ring of Kajiit), which makes you extremely sneaky but doesn't make the difficulty effectively go to absolute zero.

Perhaps you misinterpreted the post? It was pretty clear to me that he understood that more than 100% Chameleon is superfluous, and it takes at least 4 items to reach 100% in the first place.

I agree though, that giving yourself a permanent, 100% cloaking rig gets real boring... real fast. But to each their own. I tend to only abuse the phenomenon during a certain quest in a certain castle's dining hall.

I was mostly replying to ghastly who seemed proud of his 180 pts of chameleon. but yes, i agree that such an outfit can be quite useful at times, but it does kinda break the game. use sparingly for your own sanity (i'm reminded of a classic philosophical thought experiment wherein you suppose that everyone in the work suddenly took to ignoring you. Supposedly, if nobody responds to your existence or acknowledges you at all, you will begin to question your own existence. Why do my characters so often have these weird existential crisis?)

100% chameleon isn't bad as long as you don't use it to bash the nasties to death. i used this when going against lich because they can reflect spells back. what is a pure mage to do?

i often conjure a nasty and then go invisible to watch the resulting fight. or use command spells and then go invisible. as long as chameleon 100% results in a quick kill, one or two spells or blows, i don't have a problem with it.