Another is to restrict your search to scholarly, refereed journals. The search engine Northern Light indexes the full text of over 7000 journals in addition to indexing the Internet. With any of these, check the dates carefully. Resources collected by an expert may be of marginal value if they haven't been updated for two years. The real message of this article is not to give a set of rules for evaluation.
Search engines work imperfectly on a set of rules.
What we really need is to ask everyone to develop critical thinking when confronted by decisions like these. And if you are publishing your own web pages, what do you need to consider to ensure that others will realize the quality in your contributions. For a more thorough treatment of quality evaluation by a respected librarian and author, see Hope Tillman's Evaluating Quality on the Net . If you want quality in your own web pages, read the companion articles in the Publishing on the Web Forum . They will help you prepare quality, searchable information that others will find and link to.