Another author who has done quite well with indie publishing and whose opinion I respect said the best promotion was to have the next book ready to go. That makes sense. I'd already planned to put up a three-book romantic suspense series, The Dreamland Series. Book 1 is in first draft (holding nose), and Book 2 has been planned (sort of). Book 3 is anybody's guess, but it will write finis to the others.
This is the series I wrote about earlier, the one with the character who has Down Syndrome, and is "for" my young grandson who faces the same challenge of living with DS.
What I have ready is a series of stories I refer to as The Kate Chronicles. They'll make perhaps as many as 8-10 volumes of 10 short stories or 3 longer 'chapter stories' each. They 'chronicle' the 100-year lifespan of a foundling adopted by an older couple who grows up to become a doctor. So they'll probably be next up.
I have two finished novels I could put up, but one bears a second look. It's rather gritty--not graphic or otherwise against my grain, but it deals with some very realistic life situations...and I'm not sure I've done the best job handling them. It's a good story about four siblings taken away from their father (their mother deserted the family) and put up for adoption during the Depression. The oldest vows to find and reunite them. Keeping Promises is the story of her quest. It's not necessarily a 'feel good' story despite its happy ending.
The second is based on a family story of how my great-grandfather shot and killed his stepfather back in 1876. It's a 40K+ novella to which I added a sequel of the same length--so perhaps that would be two books. Four Summer Days is, in my opinion, the best thing I've ever done, and I keep thinking maybe it should go to a university press in the area in which it's set because of the historical background. I've hung onto it for probably a dozen years, so maybe it's time for it to see the light of day--and hope readers like it.
And, of course, there are various other WIPS which may or may not ever be finished. (So much to write, so little time!)
This venture into indie publishing has been a satisfying venture (though exhausting). It's like I'm at the crossroads now...which road do I choose to travel next?