This page is devoted to external resources for writing.
There are many excellent and highly developed writing center websites online, so there seems little need to reinvent the wheel.
The OWL at Purdue University is perhaps the most thorough and comprehensive website. It contains information and tips on every aspect of writing, from coming up with a thesis to writing transitions.
Jim Pryor at NYU has an excellent page on writing philosophy papers which is applicable to just about any critical/analytic paper.
Michael Tooley also has an excellent guide for writing philosophy papers, complete with a helpful checklist: