Writing Courteously by Alex Bean

When writing a business letter you want to use a positive tone and be straightforward and not beat around the bush with your subject. Since you are addressing the reader directly you should consider yourself as the recipient so that you may see what it feels like to receive that letter. If you use a negative tone it may cause the reader to not want to deal with you or your company anymore.

You should be formal in your writing, so no contractions. Examples
>Don’t use do not instead.
>Can’t use cannot instead.

You need to always identify yourself and also say if you are representing a company. This way the reader knows exactly who they are hearing from. It makes it more personal. Include any important location information or telephone numbers within the letter also.

Try not to overdue your kindness where it comes off as fake or insincere. Examples
>Avoid certain sweet phrases
>Avoid false praise

It is key to not come off as fake, if you do then the whole point of the letter may be ruined.

You should also start off with the good news first so that you pull the reader in, then they should be more aware of the entire letter and fully understand the point you are trying to get across.

Within the last paragraph of your letter always begin a complimentary close so say thank you in the paragraph.
To wrap it all up use a sincere closing. Examples
 Sincerely
 Cordially

You may not like the situation you are writing about, but if you use a positive tone and follow this basic outline the reader will be more likely to consider your topic. It is a very easy thing for anyone to master.

References
http://www.howtowrite.info/writing/how-to-write-a-business-letter/
Walter Oliu, Charles Brusaw, Gerald Alred. Writing That Works. Boston: Bedford/St. Martin's, 2007.