Writing good philosophy is not easy. Fortunately, there are a number of excellent online resources to help you improve:
Jim Pryor's Guide to Writing Philosophy
An excellent basic guide to writing philosophy papers, with helpful examples and templates.
An Annotated Sample Philosophy Paper
This beautifully produced Prezi by Angela Mendelovici allows you to scroll through a sample philosophy paper with helpful notes highlighting key writing techniques.
If you're looking for a more in-depth writing guide that will also help you with your writing in classes outside the philosophy department, we strongly recommend They Say / I Say: The Moves That Matter In Academic Writing, by Gerald Graff and Cathy Birkenstein.