According to a 2007 judgment against Hormel Foods, Inc. we are allowed to call Internet junk mail "spam", provided we use the term in lowercase to differentiate from the populate "potted meat product" that originated the name. The reason we use that term goes back to an old Monty Python skit about a restaurant that only serves the meat product and they keep repeating the word over and over until you get sick of hearing it. Which is very much like the kind we get in email, too.
Once you get on a spammer's list, you will never get free again. Spam companies do not obey rules; in fact they go to great lengths to break the rules by making unauthorized use of other people's computers and false identities to send out their disgusting junk mail. So don't even think about replying to spam or requesting to be removed from a mailing list or complaining to company that makes the product, because they don't care. The reply address is fraudulent, and the physical address is usually an anonymous overseas PO box.
So the only way to avoid spam is... never give your email address out to anyone for any reason. I'm only slightly kidding (computer geeks call this "ha ha, only serious"). Obviously at some point you need to give your address to SOME people, or the ones you want to contact you will not be able to. The thing to do is be highly selective of people you give that address to. I *strongly* advise you to create multiple addresses for varying levels of trust. My friends and family, who know to be careful how they use my address, get my real, permanent address. Public discussion forums where any random stranger might see my address and misuse it get a totally different address, which might change at any time if and when it starts accumulating too much spam. This is also the address I give to new acquaintances (including relatives) who may not be as careful as I'd like in handling private information. And when I am required to fill out an online form to purchase something or open an account, I have yet a third address that I change any time there is even a hint that it might be misused.
The hard part to do is to instruct your trusted friends how to avoid compromising your privacy. Anyone who likes to forward you all the latest jokes and pictures, anyone who happily hands your address over to those online "e-greeting" card services... give them one of the disposable addresses.
Bottom line, to keep spam-free an address should NEVER appear anywhere except as the sole recipient from a single sender. Do not put someone's private email address in a long list of CC (carbon copy) or "To:" addresses; use BCC (blind carbon copy) instead. Never give a private email address to an e-greeting service; those exist only to collect addresses they can use to send out advertisements. Never give someone's address out to another individual without the address owner's permission.
If you are already drowning in spam, I'm afraid there is no cure. You are just going to have to abandon that address, no matter how perfect it is for you, establish a new address, and follow the above rules about giving your new address to others.
Is all this paranoia worth it? Well, most of my friends receive hundreds of spam messages a day. I receive 10-15 messages, and all of them come to the first address I had, which I gave out a little too freely before I learned who could and could not be trusted with sensitive information.