I never suggest anyone to buy installs as not only it can badly affect your retention rate but can also cause your app to get banned on play store.
I would suggest you take the longer but more beneficial route of ASO.
1) Do Keyword Research The best way to start your app store optimization process is to reflect on your app and what you want to offer your users. I would recommend just start brainstorming and building a list with words, that you think could describe your app. You…