What are some of the best practices or etiquette that should be followed when writing business e-mails?

Answer 1

http://esl.about.com/od/businessenglishwriting/a/bizdocs_3.htm

http://highered.mcgraw-hill.com/sites/0070880581/student_view0/sample_letters.html

http://www.businessemailetiquette.com/