Both of these links are very insightful on the specific marketing strategies that can generate the most users visiting your site or mobile app.
Talks about how to achieve effective SEO that will bring you free traffic to your app. SEO in my opinion is one of the most useful strategies to build users, but feel free to share you own thoughts as well about marketing tools.
Links:
https://blog.kissmetrics.com/high-performing-pros/utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+KISSmetrics+%28KISSmetrics+Marketing+Blog%29