You should be speaking to the readers as though they are friends, so keep it on a personal level rather than strict and serious. For one thing, make sure that you always write as though you were writing to a friend. Writing an actual business letter is something different altogether because that has a more stern and strict tone to it. You can reach out to thousands of potential customers in just a matter of seconds once you send out your sales letter.
The first part of writing a sales letter is to write the headline. This is basically the title of your story, of your letter, and it should be captivating. Considering the headline should be about four to five words long that may seem a bit silly but it is true. This is where you need to captivate your readers otherwise they are probably going to just toss the letter away.
You can keep the tone more sarcastic if you want or not, just be sure to use a title for the letter that is going to grab peoples' attention. Use the body of the letter to be where you give your sales pitch and where you discuss in as much detail as possible what it is that you have to offer. Whatever products or services you are offering to your readers, they need to be made aware of these. Today the industries are all so congested that people are not going to be interested in a business if they think there are five thousand more like them out there.
Take time when writing a business sales letter and make sure you get your point across. They should not be left hanging at the end of your business sales letter, wondering what action they are supposed to take. Even if you only bring in a fraction of what you were hoping that is still more business and that is what matters. Practice makes perfect when it comes to writing good sales letters.