We all like getting things for free, but to get the free stuff we usually must provide our email address. There is always a risk that this will get us more junk email. Let's see how we can avoid the junk but still get the goodies.

Only provide your email address to sites that have an appropriate privacy policy.
Use a free (and disposable) email address when you suspect you may get on email lists that don't interest you.
Most online forms provide a checkbox to select whether you want to receive email from them. Check or uncheck as appropriate
Many online forms have a checkbox which asks permission to share your information with third parties. Check or uncheck as appropriate.
Avoid entering your email address in online guest books or other places where it will be displayed on the Web. Spammers use programs called bots to harvest these.
Never reply to unsolicited email even to request removal. It just verifies that your address is valid.
Use a bulk email blocking service like the one described in the related features below.
Tips:
Some junk email is inevitable. Learn to recognize it by the subject or other headers and delete it without bothering to open it.