You might take a look at a book titled Playing the Short Game: How to Market and Sell Short Fiction (2014) by Douglas Smith, an award-winning SF author.

The book was serialized online (pre-publication) at Amazing Stories, where I read it free, but I don't think the serialization is still available. Was filled with good step-by-step info.

https://www.amazon.com/Playing-Short.../dp/1928048226