Try to educate and be educated. In particular, if you ask a question, you should send a summary of the responses to the list, thus allowing others to learn along with you. The most important part of your posting is the Subject field. Your message will be rejected without it. The subject line should not be longer than 40 characters.
People screen incoming e-mail by the subject line, so make it clear.
Some people check e-mail on slower modems, often at home in the evening, so please be considerate. Send your longer file to the administrator instead. It will be placed in the archives, and you only need to post a pointer and a description. It will be distributed automatically to all subscribers. As a courtesy to the other subscribers, it is a good idea to include your name and e-mail address at the end of your message so that people may contact you directly.