Dave Dobson’s books:
Inquisitors’ Guild series – epic fantasy/detective/humor
Daros – Sci fi / space opera / adventure
I have had a similar experience to yours for most campaigns. One thing that has achieved at least a positive return on investment is very low bids ($0.10 to $0.15) on a lot of related-but-not-primary keywords – e.g. other indie authors, series, and book titles, or words that relate indirectly to my stories. I got a big list of these words as a reward for a paid membership to BookSniffer (which has produced nothing else for the money – would not recommend yet). With the low bids, I rarely win ad placements, but the low conversion rate is much more economical at a low ad costs. I’m about breaking even on the ads with KU providing enough gravy to make it worthwhile. I haven’t tried scaling it up or applying to other books yet, but I am planning on seeing what happens when I do.
