Here is a guide to writing philosophy papers that I have been giving my students in essay courses for several years. Some of it applies to writing philosophy, but most of it applies to any sort of serious writing. Suggestions for improvements would be most welcome:
Guidelines for Writing Philosophy Papers.
One of the most useful on-line guides to scholarly writing and editing I've seen is the Purdue University On-Line Writing Lab (OWL):
— Most recent update, November 23, 2016