Are you about to approach further or tertiary education? Do you want to improve your writing skills at work, and be better at getting your ideas across. Massive Open Online Courses (MOOCs) are free online courses run by some of the world's best universities. At this link you can access a MOOC in effective writing from the University of California. There are many lessons here in essay and argument construction, sentence building and tone. Remember this is an American course, so some of the nuances of grammar might be different.