Create site to promote own app

Elements of such microsite:

• App screenshots;
• Video (for example, https://www.youtube.com/watch?v=yXYN8lj8XrI; https://www.youtube.com/watch?v=8xPUdFaraoQ);
• Content and text about the app – What does it do?
• Features and benefits – Why does someone want it?
• Links to download sites – iTunes & Google Play;
• Contact information – especially for media;
• Social media links.

Source:
http://www.accella.net/creating-a-microsite-to-promote-your-mobile-app/

Check your app name with such services as

• Google Keyword Planner
• SensorTower
• AppTrace

Source:
http://www.accella.net/mobile-app-marketing-picking-a-name-for-your-app/

Promote your app with

• Screen Shots 
• Brief Descriptions
• Quotes from the publisher or developer 
• Press Releases – announcing the app’s launch, updates or big news. 

Source: 
http://www.accella.net/creating-a-press-kit/