But if you want to get 4K-5K once, you only can buy installs from install providers which can gather real users together.
1. Buy installs directly can help you on app ranking with targeted keywords related to your App. ASOtop1 is offering this service to help it on keyword search&install from real users. When users do search the keywords you choose, they will find your app. With this method, your app will rank top in App Store search results.
2. Gain positive reviews--If one app will get reviews, it must be installed firstly. BestReviewAppis one site to offer organic app install, play, rating and positive reviews from real users all over the world. This method will help a lot for app overall ranking.
While if you have enough time to wait for more installs, you can try these free methods.
SEO Landing page: You may create an landing page for your app. Then you will get some keywords related to it with SEO campaigns.
Social networks: Post the download link, website, landing page address on Facebook, Twitter, Linkedin, Instagram, etc.
Press Release: 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.
Cross promotion: 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.
Offline promotion: 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.