Take advantage of the built-in junk mail filters inside your e-mail client. In addition, configure your own filters to automatically trash or delete incoming e-mail that contains certain keywords.
By using a combination of various filters you can noticeably reduce the amount of spam reaching your inbox. You can set up as many filters as you like in your e-mail client. It is always wise, though, not to automatically delete the filtered mail until you are certain the filter is properly configured. You can always change it later.