you just pulished a new app thinking about different ways to promote
your app. I can recomended for you to build marketing strategy based on
main point to-do such us:
Build teaser website. Do this a month or two before your launch to collect email addresses of people who would like to know when the app launches.
Start a blog. Attach it to your microsite. Write interesting content that will draw people to your website.
Share your content. Use your Twitter, Facebook, Google+ and LinkedIn profiles to promote the app several times in a week.
Create a product video. Make it creative, funny, thought-provoking or personal. Tell the story, but in a way people can identify with.
the last but not the least: do not forget about gorgeous icon and
presentation of your app with lots of pictures or even making video
Hope this helps