● Use suggestions from Play Store and App Store search fields. Put in each keyword to maximize the diversity of your keyword could. For example, for “clash” you can add suggestions “clash of clans”, “clash royale”, “clash of clans 2”. Try each keyword to find all suggestions for your app.
How to check keyword collection quality?
Each search request will be shown with the statistics of clicks on icon, number of installs and conversion rate. The higher is the conversion rate for the keyword, the bigger is the relevance of it for your app. The high conversion rate by the keyword shows that the user has found what he was looking for at your app page. So, you need to focus on this and all related keywords and plan their promotion by keyword installs.
If the conversion is low, the installs by the keyword are accidental. That means you should not start promotion by them.