Welcome! I upvoted you and will follow. Thanks for the tips, especially the ones about headers and text! I have been on Steemit just a few days myself. I hope you will check out my Intro post too and upvote it. To answer your question, I'd say the the most important thing I learned for me as a professional photographer who plans to post lots of photographs, was that I could drag and drop images into my posts! I had originally read that I would have to use an image sharing site. I was not too crazy about that idea!