This is probably the one most effective method of warding off the spammers. If you don't give out your primary email address except to trusted individuals and organizations you can keep a nice clean mailbox. Use this address when you think you may be exposed to a junk emailer. When you do start getting too much spam to that account just cancel it and get another. You should also use a disposable account if you post messages to the Internet news groups.
Spammers often use software that combs newsgroups for email addresses.
Just Say NO to MLM's. In my opinion these schemes are one of the biggest nuisances on the Net. The best way to avoid these jokers is by learning to recognize them. If you come to a web page that is one big sign in a large font that tells you about this great deal, avoid it. If if looks like and MLM, if smells like an MLM or if it tastes like an MLM, avoid it.