Launching a mobile app

Has anyone built and launched an app?

There is an overwhelming amount of information on the web and I’m cautious that there is a low ROI for a lot of the stuff there since I have limited time resources.

I’m curious what specific strategies provided the biggest bang for the buck in your experience?
If you were launching your app, what would/did you focus on?
Any pitfalls you see people doing that you would avoid?

Cheers for any advice!

There are a lot of things to consider. of course what kind of app and target market or audience?