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.
Business writing should be clear and concise. Take care, however, that your document does not turn out as an endless series of short, choppy sentences. Keep in mind also that “concise” does not have to mean “blunt”—you still need to think about your tone and the audience for whom you are writing. Consider the following examples: After carefully reviewing this proposal, we have decided to prioritize other projects this quarter.