Letter of recommendation: Ask early
Don't wait until the last minute. Instructors are flooded with college letter of recommendation requests at the end of the semester (as well as near application deadlines), and you don't want your letter to suffer as a result. If you approach your instructor a few months before the deadline, you will avoid putting him or her under pressure, and you give him or her plenty of time to ponder your performance. As the deadline approaches, you can always send the writer a friendly reminder of the impending deadline.
