This is the kind of promo that don’t cost anything but time.
1. Create graphics w teasers
2. Do a coming soon post 4-8 weeks before release.
3. Offer ARCs 4-8 weeks before.
4. Post the graphics I made earlier on social media with links.
5. Do Flash Giveaways.( offer Epub or mobi, since most e-readers cannot read pdf in a good way)

This is all  small things, but I think it is something many authors forget about. I do some of them but in a haphazard way. I need to get more structured, which is part of the reason I  wrote this list
It all boils down to that you have to tease readers, or they are not going buy your books. Or at least that’s the case with me.