I've found some of the best training available is in discussing controversial subjects (like religion) with a mixed, but curious and respectful, group. The big

I've found some of the best training available is in discussing controversial subjects (like religion) with a mixed, but curious and respectful, group. The biggest drawback is that it's hard to find such an audience. One of the best forms of training this circumstance provides is immediate feedback any time you fall short. If you're not clear in your terms, meanings, and references people will respond with misunderstandings. If you're too verbose, they may not respond at all. If your writing is poorly structured, they will be confused as to what point you were trying to make. And if you do a good job, you'll get meaningful and interesting comments and criticism, which will help you refine your ideas and be better able to write about them in the future.