To Rank your App high on Google Play, you need to keep in mind following On Page &Off Page Factors

Off Page Relevance Factors

As per our Technicians, following Off page factors are the most important ones within the app stores.

• Ratings/Reviews/Comments : User Rating is emerging as a very important element in the Ranking algorithm of App Stores. It depicts the user’s experience with the app.
• App Speed & Size : Performance of app also plays an important role in the ranking process in terms of response times of the app, it should not be choppy and slow to respond, and the size of the app is small.
• App Updates : What is the frequency of updates in the app? Is it continuing to create new features and optimize for new OS releases?
• Social Mentions : What kind of buzz is the app generating in the traditional web ecosphere?
• App age : For how long has the app existed and is the user base increasing with time?
• Brand Trust : Is the app released by a maker, as this ensures that the app has undergone a significant QA (quality assurance) process.

On Page Factors

As per our Technicians, following on-page factors are the most important ones within the app stores.

• App Title : Natural usage of Keywords in the title appears to be one of the most important relevant signals.
• App Description : Appropriate keyword usage should also be used within the app description.
• Keywords Data : Choose Keywords that best describe your app, and separate each keyword by a comma.

Some advice for improving app store seo search

First, you can use the keyword tool in Google Adwords or Wordstat Yandex tailored to your country, to get ideas for popular search phrases that are relevant to your application
Remember, that listing the aso keywords, use commas only, no spaces!
Also you should not come up with the name of non-existent words. Ideally, app store optimization keywords in the name of the application must contain at least one main word. This will significantly increase the chances of an application to be found;
The most important thing in the description - the first line. Make it as informative as impossible;
Do not forget that there is a limit of 100 characters for keywords;
Use such services as appstorerankings.net, searchman.com and other similar successful app store optimization services and track competitors, but do not forget to double-check their work
Do not use other brands and company names. Otherwise your app store marketing won’t be effective.