1. Spend time on your letter. Someone once said, "With part-time effort, you get part-time results." This is especially true in letter writing. You can expect to spend several hours, or even several days, on a letter.
2. Write a draft, then let it cool off overnight.
3. Rewrite if necessary.
4. Use a strong close, like these: "After you have had a chance to review this letter, I will call you to get your reactions." "I will call your office next week to arrange a time when we might be able to get together. If you have any questions before that, please call me at."
5. Avoid weaker endings like these: "Please call me at your earliest convenience." "I believe that a meeting could prove to be mutually profitable, and ask that, if you agree, you contact me so that we can arrange a convenient time." "Thank you for your consideration. I am available for a personal interview at your earliest convenience and look forward to hearing from you." "In the next week or two when your schedule permits, let's meet and discuss my aspirations in more detail. Please give me a call." "I look forward to your reply."