Link Early, Link Often
When building a new site or creating new content, the notion of external linking is often a matter of concern for search engine optimization professionals. If there's a best practice when it comes to external linking, particularly for bloggers, the answer is this - be considerate of those reading your material.
In a new video from Google's Matt Cutts, the question of best practices for external linking was raised and the answer from Cutts seemed an honest and reasonable one. Publishers, according to Cutts, should give credit to the primary source when producing content on their sites.
Cutts also indicated that it should be best practice to include links at the beginning of a post/article so as not to force the user to seek out the original source of information - essentially, don't make website visitors work hard than they have to in order to locate information.