There are quite a few different ways. The links above will help ya. But I can tell ya now that there are a few things to keep in mind:
1.) Use names. You need to sound as though you are talking/communicating to a person & not a thousand. If you know the other party has the name Bob Smith, don't start the letter off as "Dear sir." ONLY do this if you have no other real options. If the guy's name is Bob, start with "Dear Bob."
2.) Mentioning a profession can help a lot. ppl feel better knowing they're dealing with a pro of a trade (at least if the trade was internet-related). Under NO circumstance should you refer to yourself as a domainer or domain investor. Both of those titles carry a load of hate. ppl resent them. Start something like, "My name is Jane Doe. I'm a graphics designer from Las Vegas, Nevada." Don't put "I'm a domain investor." That'll likely get your email deleted.
3.) Don't mention a price. You are NOT trying to get a buyer right now. You are trying to get interested people to mull over your domains. Too many noobs will put a price in their letters ie "This premium name can be yours for $1,288!" No--let them know that if they're interested, they should inquire. If you get that magical reply of "How much?" then you know you've done well.
4.) Propaganda doesn't work. Don't try to pretty up your domain. Don't try to make your letter sound too pompous. This DOES NOT work. Never ever ever ever ever EVER refer to your domain as 'premium.' Spammers and unrealistic sellers have used the word so much that it's lost its meaning. Put 'premium' on a permanent blacklist. While you're at it, add a few other choice crutch words, namely adjectives like 'great' and the cliched 'only' ie "This can be yours (note: never use this expression, either) for only $1,000!" Never use an exclamation mark, as it looks too zealous. And again: NO PRICE!
There are many others but these are the biggies you need to know. Others can be free to add to this if they want
You're right. I should have worded the titled differently. All I wanted was a basic outline of how they do it...not their actual letter that they send out.