Do:

• Use appropriate stationery and a clean, neatly addressed envelope
• Check and recheck (you and someone else) for grammatical errors, misspellings or typos, correctly spelled names
• Write to someone specific
• Sign with a blue or black pen
• Include enclosure(s)

Avoid:

• Form letters and mass mailings
• Obvious corrections
• Anecdotes and gimmicks
• Lies, misinformation, erroneous data
• Personal information (age, weight, marital status, race, religion, etc.) and photos (except in performance-oriented fields)
• Demands