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.
Reread the description of your task (for example, the advertisement of a job opening, instructions for a proposal submission, or assignment prompt for a course). Think about your purpose and what requirements are mentioned or implied in the description of the task. List these requirements. This list can serve as an outline to govern your writing and help you stay focused, so try to make it thorough. Next, identify qualifications, attributes, objectives, or answers that match the requirements you have just listed.