As my experience, these methods can help you promote your app. While it will lead good result, it also will take much longer time.
Press Release will obtain very positive results thanks to the “newness” factor associated with Apps. You will post your app features on the press release sites, related column, etc. Create your own blog to share your app details, such as new version, new feature.
Once you published your app in Store, you can market it with cross promotion with other apps by installs and reviews exchange. It is free while it is still hard to find that publishers like you. You may try some Cross-promotion networks (CPN), Facebook group or exchange forums.
Make a Video
Videos shows great ability even just 30 seconds, it has power to show users why the App is worth a try. Make up a story of your app? Show the real life? Yeah, both OK.YouTube is the good site.
Make connect with your friends and families. You may ask them to help you spread your app in their relationship circle. Also, participate in meetings or conferences that are relevant to your App, and make full use of it to build partnerships.
It is something like PR, which also helps app/app link with essays. It is your own blog, we mean you can introduce any information of your app. And you post the blog in some marketing sites like Quora to get more external links.
Social media network has strong power to gather users, such as Facebook, Twitter, Instagram. It is necessary to post app link there.
There are 3 more paid ways below. It may help you in future.
All apps are made into different categories with keywords. So Keyword Optimization is still far important than other factors. You can buy installs from real users gathering in some site, such as ASOtop1. The app will generate many downloads in a short period which also will push app rank higher. Of course, higher ranking app will attract more potential users.
No matter your app is paid or free, Cost-per-install ad payment method is a good way to show ads in the ad network. As install is the final goal for app, CPC or CPM will not be available for apps comparing with CPI.
App reviews and rating
Apps that have more positive reviews is more likely to be downloaded. Therefore, you can invite your friends, families, followers on social media and users to write positive reviews on your app. Also, you can buy reviews from BestReviewApp which is an agency dedicated to offer positive reviews and high ratings for iOS, Android and Mac app from real users around the world.