Generally, I write about topics that interest me. I don't think about what is popular or what I think other people might like to read; I write about things that I'm passionate about, that intrigues me. For example, my first couple of books were about rock stars because I love music. My second two were about vampires because I found the topic intriguing (and specifically, wondered what if vampires were different than how they're portrayed on television and movies?) and finally, I started to write about gangster and criminals. This subject intrigued me because I was drawn to the antihero concept, however, the longer I write, the more I question how it relates to our current world. With all the corruption, collusion and everything else we are seeing in the news, it's becoming more and more evident that it's not always clear who the 'good' and 'bad' guys are anymore.
Having said that, more specifically, regarding chapter to chapter details, I mainly follow my instincts. I have a lot of snippets of conversations and scenes that show up in my mind and I immediately jot them down and eventually they find a place in one of my books. Often I have no idea how or why until it actually happens.
Most of the time, I simply follow the storyline and the characters to see where they take me. Characters have their own unique personalities and like people in everyday life, you can often predict how they will react in any given situation. That in itself usually moves a story in the direction that it's meant to go.
My ideas come to me all the time. The key is to be open to everything without questioning it. In the end, it usually finds a place in a book.