Personal pronouns (like I, we, and you) are important in letters and memos. In such documents, it is perfectly appropriate to refer to yourself as I and to the reader as you. Be careful, however, when you use the pronoun we in a business letter that is written on company stationery, since it commits your company to what you have written. When stating your opinion, use I; when presenting company policy, use we.
If you’ve done that well, they’re going to be asking themselves “How can I make this happen?”, which you answer in the last section of your letter by proposing an action they can take. “Call me at 鴔) 555 to arrange an interview” or “Let’s meet next Thursday to discuss this proposal” or “Order your copy today”. Don’t leave the action for your recipient to figure out. I think a lot of time we lack the confidence to ask for the action we want, and we give ourselves an “out” by leaving it unsaid, hoping they’ll figure it out themselves.