One of the best ways to avoid receiving spam is by being cautious of what websites you provide your email address to. Only provide your email address to those websites with good reputations.
Be aware that some smaller email accounts that people have could mistakenly be entered into your junk bulk box because the spam filter does not recognize it.
Companies such as .Mac, or AOL, that require you to pay for an email account have more sophisticated filters that will help distinguish personal small email accounts from junk email.
Keep in mind that it if you receive important emails on a regular basis, it is wise to purchase a sophisticated spam filter that will eliminate junk mail but will not lose an important email.