Robin Nobles of the Academy of Web Specialists and Search Engine Workshops warns against a very common mistake: Never send out a "blanket" email to hundreds of sites asking for a reciprocal link.

Instead, "Make each email personal. Mention something that you like on their site. Give the URL for their links page. Discuss one of their products. Ask them a question. Do ANYTHING to make it clear that this is a personal request and not a mass-generated email."

The more you compliment their site with specific examples, the more likely a webmaster will consider your request as an honest reciprocal linking campaign. No one likes spam, so take five minutes to personalize each request.