1. Kindle books are focused, and SHORT: focus when you write
Before Amazon launched Kindle, markets for short stories were pretty much non-existent. Kindle readers changed that. Today, if you write fiction, and aren’t writing short stories, you’re missing a good market.
You can reach that market via Amazon’s Kindle Unlimited (KU) program. It’s had big effect on self-publishers: it can help you to build your brand as an author. You do this by creating shorter books, specifically for KU.