Even if things are changing fast, and you shouldn’t listen to too old advice, I think most authors, no matter if they are self published or not, agree on the fact that series sells.
In this moment, I have 4 novellas sitting on my hard drive that are the first in a series ( Frosthold, Queen of Sind, Daughter of the Dark, The Wild Hunt.) I could focus on revising them and getting published, but the truth is that some of them needs a lot of revision. All of them will get published, but I don’t think it is a good strategy to let book one in a series be published and then there are 3 years before book two gets published.
Mainly because for me one of the points in writing a series is to release the short stories and novellas close to each other. This both helps build sales and keep up the momentum on the series.
So my plan is to focus on getting the Portal Universe series out first, and then focus on other series. This doesn’t mean I will not write sequels to other books when I have time. Since I need a break from the Portal Universe sometimes. Then there is the fact that I am ahead of my publishing schedule right now. I have written the books that I intend to release in 2016 already. Which is a relief, to be honest. So maybe I will write the sequel to Frosthold this fall. 🙂 Or at least finish the type in for Frosthold. Or maybe I will work on something else entirely.