Hello and welcome to steemit it sounds like you have plenty of experiance to draw on when writing your content. you don't have to specialise in just one area many of the top content creators don't, but carving a niech foryourself can help you get noticed and earn more especially if no-one else is covering it yet.
As for yours posts @merej99 wrote this great article it's about SEO but has some useful tips and a link to a mastering markdown article from git hub that will help you make them look more attractive.
Good luck and happy steeming.