OP - I have (well more accurately, my firm has) helped launch dozens of apps over the years. there are certainly some broad stroke best practices to consider or familiarize yourself with, but by and large the best path early on is a customized strategy that fits the market/target of your app audience and also to utilize as much sweat equity as possible (since, I imagine, your marketing efforts will involve an entirely bootstrapped budget.) also I'd say that a big part of making an app marketable goes into the development and design side (for example: the most important part of successfully marketing your app is making sure the app is available and stays online through heavy usage/is easy to use through thoughtful UI/UX.)
there are a ton of little tips and tricks (everything from how to tag your app for easier discovery [or what is called ASO] on the app store to how to leverage content marketing/social media and so on) but I've posted a blog post my team put together which you may find useful as a simplified starting point. There are certainly other resources out there but these are what we will commonly share with our clients along the way (*mods if you prefer me to share these via PM with OP let me know.*)
https://www.farshore.com/blog/ten-wa...-ios-app-2016/
If you're looking for any specific feedback or insights feel free to PM me and we can take the conversation offline.
BOL and welcome to the appreneur game.
