It has been less than a week since I launched MERNKit and I already have some wins. It really does get easier to launch a startup once you've done it before. Here is some of what I am doing to build initial traction while I work on SEO:
Experimenting with Facebook and Google Ads
Post in threads where I think my potential customers are whether that is Indie Hackers, or Facebook groups.
Most importantly, I email every person who signs up for a live preview at https://mernkit.com. I ask for feedback on why they have or haven't purchased, and if they have purchased what I can do better. Rinse and repeat :).