http://busyteacher.org/4650-how-to-teach-writing-6-methods-for-generating.html
http://busyteacher.org/6214-how-to-teach-summary-writing.html
http://busyteacher.org/2971-how-to-effectively-teach-english-writing-skills.html
http://busyteacher.org/6451-7-strategies-for-elaboration.html
http://busyteacher.org/9359-how-to-teach-argumentative-essay-writing.html
http://busyteacher.org/12329-get-students-writing-6-post-it-activities.html
For you, I would recommend Successful Writing Proficiency by Virginia Evans, Express Publishing, it would give you insights, structure, better understanding and cofidence in teaching writing to your students. You can even base your activities around the rubrics in that book just using more relevant, more current material for 15-17-year-olds.
Sophia