UPDATE 2020: Hi folks! I've gotten so many great responses from people over the years about these journals, I've decided to give them a bit of an update (also because there are so many new resources out there that it's been hard to keep up). I also want to make these tips more palatable to those who don't have interest in doing solely fanart, as I've seen a lot of artists be successful in doing almost purely original work. So I hope these journals continue to be as informative and helpful as they have been over the years!
After being a member of several artist alleys for 10+ years, I thought I should share my knowledge in a practical guide.