You've got to be a good reader. So whatever genre that you're interested in, read a lot of books about it and it's better than any kind of writing class you'll ever take. You will absorb techniques and then in a lot of cases you can just start writing using the style of the book or the author that you admire and then your own style will emerge out of that. Be a diligent reader and then try to write seriously, professionally and approach everything in writing in a professional way.