Deciding what to work on now and next comes down to backing into dates of a marketing plan.
Want me to try that again in plain English?
I currently subscribe to the theory that the ideal release schedule for a self-published series is one book per quarter/four books a year. (Yes, there are lots of other theories out there, so YMMV.) I have four series I want to publish. Basic math says that equals sixteen books released in a year. Basic sanity says that's never going to happen. Creatively, I cannot focus on only one series because of burn out. (It's like having pizza every day; awesome at first but then you can't stand the sight, smell, or mention of it.) So, more than one series, but less than four. Three series is a book released every month. Again, not remotely realistic for me. So, knowing my personal limitations, I'm going with two series.
Which two? The one I've already launched and the one with the hungriest audience. Both are sub-genres of Fantasy. I don't want to confuse or lose any audience I'm fortunate enough to build by jumping into an unrelated genre. I don't (yet?) have that kind of dedicated following.
Eight books drafted, edited, and produced in a year is...frankly still beyond my abilities. How do I address that? Well, I've already screwed up the release timing of my High Fantasy series, so I'm going to accept that four 150k books a year isn't going to happen. That series is not going to fit the ideal marketing schedule. Not now. Not ever. Fortunately, High Fantasy audiences tend to be more forgiving of long gaps between releases. I'll shoot for one release every nine months.
My second series is Urban Fantasy with half(ish) the word count of the High Fantasy, yet a much higher reader demand for more frequent releases. So, four books per year has to happen for this series to succeed in a glutted market.
Now I'm looking at five books a year. Possibly still unrealistic for someone who's only managed to launch one book in the last eighteen months. How do I give myself a fighting chance? I'm taking advantage of my foible and I'm stock-piling. I'm writing four books in the Urban Fantasy series before I launch it, so I have one year of work in that series ready to go while I write the next year's planned books.
When I wrap up a series another one can slide into its place. That is The Plan...and we all know the plan is the first casualty.
That, ladies and gents, is how I determine on what I'm working now and next.