If you want to be treated as a professional, you must act like one. This goes from checking spellings and grammar (and not relying on your computer here) but, more importantly, in terms of attitude. It’s a question of being confident but never arrogant and not thinking of yourself more highly than you ought or being a doormat.
You can never have too much paper, stationery, ink or toner cartridges or information. In most professions there are journals for that market. Writing is no exception. And to be taken seriously as an author you need to know what’s going on out there. I use Writers’ News, Writing Magazine and Mslexia.
Writers are underestimated. Someone has to create the stories. Entertainment on TV, stage, film, radio and so on need stories. The country’s tourism industry is fed by writers - almost exclusively in the case of Stratford-upon-Avon. So can someone please stop all attempts to get rid of copyright? It isn’t unreasonable for authors to want to earn a living!
Just as you shouldn’t underestimate fellow humans (if only for our stupidity capacity, it is endless), writers shouldn’t under-estimate characters. Let them develop their lives. Let them surprise you. The story belongs to them. You are the conduit through which it ends up on the paper. Character led plots are easier to believe. We want the characters telling the story.