Image source: The Periodic Table of SEO Success Factors)
What would someone be searching for when they're looking for an app just like yours? That is the keyword you should be targeting. Use that phrase as well as variations throughout your listing: your title, tagline, URL, and image alt text.
Make your listing URLs more search-engine-friendly by naming them with clear keywords. When talking about your app in other places, be sure to link to your page.
The screenshots and icon you use are key. Those elements are the most important factors to drive conversions. Spiders can only search text, not text in your images--which is why you need to make the words associated with your images as descriptive as possible.
Google wants thorough content that will give visitors 100% of the information they would need in one place. Updating regularly and often is crucial for increasing traffic and for listing optimization.
You won't know if your SEO efforts are working unless you monitor your search standings. Periodically check how you're ranking for your keyword. Either use your own SEO tool or open an incognito window and search for your term. Keep in mind that you're probably only going to drive traffic if you're ranking on the first page of results.