It is well to avoid the too frequent use of the pronoun I in the letter, though care must be taken not to carry this caution to extremes. I, however, should not be omitted when necessary to the completeness of the sentence. Do not try to avoid its use by omitting it from the sentence, but by substituting a different form of sentence.
There is no objection to beginning a letter with I.
Punctuate the letter just as carefully as any other composition.
Excepting in letters of a formal nature, there is no objection to the use of colloquial expressions such as can't, don't, etc.
Unless you have some clear reason to the contrary, avoid the use of expressions that have been used so much that they are worn out and often almost meaningless. Such expressions as the following ones are not wrong, but are often used when they are both inappropriate and unnecessary.
The Close
166. Final Words. Business letters frequently close with some final words, such as, Thanking you again for your kind assistance, I am ..., A waiting your further orders, we are ..., etc. These expressions are not wrong, but are often used when not at all necessary.
167. The Complimentary Close. The complimentary close should be written on a separate line near the middle of the page, and should begin with a capital letter. Appropriateness is the only guide to the choice of a complimentary close.
The following complimentary closes are proper for business letters: