I’ve just gotten a lucky break and was offered a Web App Dev position after being stuck in stagnant web design jobs for years, I was wondering if any Web Devs and Web App Devs have any advice on how to make the most of it. All the drupal theming & config I performed at my last position is what helped me acquire this one. Since this is a career change, I’m looking for advice on how to make the most of this opportunity. What should I focus on learning? Any bad designer habits I’ll have to break? While web development is diverse, what skills are a “must have” to perfect and to become indispensable? What pet peeves do developers have about designers who are make the same transition? What do you wish more people from design backgrounds would learn before making such career changes?
I’d been trying to make a transition to “web development” from “web design” for a long time now. Despite taking initiative and learning front-end and web app skills on my own, this went unnoticed and unrewarded by my former employer who mismanaged me terribly and then outsourced my job.
The new position is for Web App development (drupal), while my programming skills are geared for front end (javascript & php for templates), the new employer understands and is willing to train me. This is RARE opportunity 
My primary challenge is learning the back end skills without having a CS or IT education (I have a BFA, which hasn’t helped me much). The job will have a lot of UI/UX work as well.
Being stuck in a position where one works for non-technical morons was harmful to me because I had no mentor. I’m somewhat naive about how Web Development is diversifying and maturing. As a result I’m unsure of: which direction I’d like to go, what would be a better web developer niche for my skills, what skills I need to quire to become less dispensable than I was in web design and more desirable to prospective employers in the distant future. My first guess is to specialize in UI/UX since my art background would be helpful in that, and I have a long way to go before I’m confident in my programming chops on a back-end level. While I know there are some who say “do what you love”, I’m also concerned about wages. I’d rather not corner myself in a job with limited wage growth and a lack of upward mobility.
Any words of wisdom would be much appreciated!