Evaluating Resources (Univ. of California Berkeley) - Covers scholarly vs. popular publications, primary vs secondary resources, web resources, authority, documentation, etc..
Using Primary Sources on the Web: Finding, Evaluating, Using (American Library Association)
Jacobson Center - Offers individual writing conferences, courses to improve writing, and online help to guide students through the writing process.
See especially the Jacobson Center's Writing Process Series, which breaks the writing process down into a series of steps and offers advice and strategies relevant to the main issues confronting most writers.