Ask HN: How did you get the first users for your smartphone app?

I recently released my first android app. However, there have been only three downloads. How did you get the first couple users of your app? Did you buy ads to promote? Or were those just random users who found your app in the store?

(FYI: https://play.google.com/store/apps/details?id=com.johannes_mittendorfer.abfahrt)