The following websites have information on improving your writing:

http://www.osmania.ac.in/e-Education/Study%20Guides/wrtstr7.htm
Writing Lessons Learned from 200 Columns on Writing

http://writing.richmond.edu/writersweb/
Explore topics by stages of the writing process.

http://www.fas.harvard.edu/~wricntr/resources.html
Writing Tools

http://web.mit.edu/writing/Writing_Types/introstrategies.html
Strategies for Writing Introductions

http://www.ipl.org/teen/aplus/linkswritingstyle.htm
Writing Style and Technique

http://www.gc.maricopa.edu/English/essay/
The Five Paragraph Essay

http://www.writing.ku.edu/students/guides.html
Writing Guide: Guidelines for writing various kinds of papers