Hello, MMowned! I'm tired of being a leecher, so I thought I'd contribute.
Now, searching these forums, you will find many, many e-mail scam techniques. All of them have the ability to succeed or fail. It's in your hands to make it believable or LOLYARIGHTNUB.
The most common mistakes:
1) Grammar, Punctuation - I cannot stress the importance of this enough. Even a single missing period, or even a single period mispelled as a comma, can ruin your chance to have a great scam. Blizzard does make mistakes, but the people you're scamming are going to be too stupid to realize that. If something has absolutely no grammar or punctuation issues, it will be 500% more believable.
2) Language - This is also very, very important. You will notice from my writing that it tends to be very formal. This is key to a successful scam. Saying, "Hey, we saw you're trying to sell your account, you can't do that", doesn't sound nearly as believable as:
Greetings, customer!
It has come to our attention that you are attempting to sell your World of WarCraft[: The Burning Crusade] account on <website name>. We would like to remind you that this is against the Terms of Service. If you continue to violate the ToS, your account will be suspended.
~<fake name>, Blizzard
It is absolutely crucial that your language is formal and to the point. Blizzard doesn't waste time getting to the point when cracking down on rule-breakers.
3) E-Mail Address - Your E-Mail address is key. Quite obviously, something like "[email protected]" is pretty obvious, but any e-mail address with underscores or numbers simply will not work.
Ex. [email protected]
It's best to use hyphons instead of underscores, and add in another word instead of numbers.
Likewise, websites like hotmail and yahoo sound very unprofessional. If you do not have access to any other e-mail, gmail is the best option. [email protected] sounds thoroughly unprofessional and will give the whole thing away. Using hotmail, but making your address "@live.ca" is also acceptable, but the ".ca" at the end would give away a Canadian source - and Blizzard is not based in Canada. It's best to use a little-known e-mail provider if possible.
Ex. [email protected]
4) Name - If you have a name, people will also be inclined to believe you. Choose ordinary sounding names, such as Joshua, Andrew, Amy, Karen, David, and so on. UNDER NO CIRCUMSTANCES use either "Chris Metzen" or your World of WarCraft character's name. Nobody will believe you if you claim to be Chris Metzen, and your account can be banned if your scam is found out under your World of WarCraft character's name.
5) Links - Always, always, always provide a link to the ToS. Most people won't be willing to spend hours perusing it and thereby discover that Blizzard will never ask for their password. The number of people who do will be insubstantial compared to the number of people who are convinced by your link that you are the real deal. One part truth and two parts lie - stir well and serve. If you get the mix right, they'll swallow the whole thing.
Well this is all the advice I have for now, I might be updating again later, but until then, I hope this is found useful by all of you!
EDIT: Grammarlawl, I need to follow my own advice! :P