Learning to write (better) with someone to guide you is wonderful. When you you're ready to supplement tutoring or classroom instruction, you will find that the products of many generous people await you at no charge if you're willing to dig in. Here are some of my favorites:
The Chicago Manual Online http://www.chicagomanualofstyle.org/qanda/latest.html offers a free subscription to a funny, practical Q&A service. Worth every minute if you have grammar and usage questions or need ammunition to explain something to colleagues, or, tactfully, to teachers.
Copyblogger http://www.copyblogger.com/write-with-a-knife/ is a smorgasbord blog, with some simple advice on how to write tight marketing copy. Most of the tips are useful for tight academic copy, too. This link is for tips on ruthless editing, but there are others on persuasion, dumb grammar mistakes, etc. An easy reference.
Geoff Nunberg (University of California, Berkeley) writes on the on the passive voice in this is nuanced look at when to use the voices most effectively (print essay). Yes, of course, Strunk and White come up. http://people.ischool.berkeley.edu/~nunberg/passive.html And here is his presentation on National Public Radio's =Fresh Air: http://www.npr.org/templates/story/story.php?storyId=103709904&ft=1&f=13
The Online Writing Lab at Purdue University offers more than 200 free resources on writing, grammar and mechanics, style guides, English as a second language, and professional writing (e.g., resumes). An old site, but really useful. http://owl.english.purdue.edu/
This University of North Carolina handout on the passive voice reviews myths about the passive voice and offers great tips on avoiding the passive in academic, scientific, and technical writing--how to convert those vague, "professional" sentences into meaningful, precise, convincing statements. http://writingcenter.unc.edu/handouts/passive-voice/ They offer other handouts as well. This is a super resource for English as a second language students http://writingcenter.unc.edu/handouts/
More to come next post! If you have specific interests, ask away.