App Store Optimization (ASO) is the first step to succeed in mobile app marketing. ASO helps your app to be found within the app stores and generate extra downloads or sales. ASO is considered the mobile SEO for applications.

On-Page Relevance Factors

Based on a study of more than 200 app searches, it would appear that the following on-page factors are the most important within the app store.

App Title: Keyword usage in the title appears to be one of the most important relevance signals. It is currently unknown whether it’s a direct signal (keyword usage means higher ranking) or an analogous one (keyword usage results in higher click-through rates).
App Description: Appropriate keyword usage should also be used within the body copy…errr app description.
Keywords Data: A good old keywords tag, you ask? Yes, but it appears Apple is already de-weighting its impact. Expect keywords tag to get phased out altogether as app development becomes even more accessible to a mainstream audience.

Off-Page Relevance Factors

Unlike Google, Apple has total access to everything that happens within the confines of an application, which means there’s a boatload of data to determine user appreciation. The following signals can be used to compare apps within similar categorical clusters:

CTR: What is the click-through rate when served in a higher position?
Usage Weights: What is the average frequency of usage within the app?
Discard Rates: How frequently is the app deleted? What is the average life of an app on a desktop?
Downloads: How many downloads does the app have?
Reviews: What is the average review score and how authoritative and authentic are the reviewers?
App Updates: How fresh is the app? Is it continuing to create new features and optimize for new OS releases?

Possible (But Unknown) Factors

I believe Apple would be silly not to incorporate the following signals:

Social Signal/Incoming Links: What kind of ripple in the traditional web ecosphere is this app making?
App age: Are users consistently and reliably using this growing app? (Think of MS Word as a desktop comparison)
App Speed: Is the app responsive when compared to its competitors or is it a heavy experience?
Brand Trust: Is the app released by a maker that has a trusted arsenal of popular/successful applications? This would likely ensure that the app has undergone a significant QA (quality assurance) process.

Where App Store Optimization is Heading

Like any search engine, the App Store appears to be transitioning from one of semantical relevance to the deeper and more powerful KPIs that revolve around user data (nearly every algorithmic shift thus far appears to support this notion).

As the entire industry matures (and becomes more competitive), success and failure in ranking will be much more focused on the quality experience of its users.
8 Tips for Improvement

Here are a few tips to help you rank better in the App Store:

Focus on natural incorporation of keywords in the title and description data
Use conversion optimization techniques and push notifications to ensure more prolific usage of the application
Keep the application “top of mind” through email and social media integration. Give your users a great reason to share, like, and follow.
Offer heavy users the opportunity to review the app. A simple push with the opportunity to rate can give your ambassadors a platform to evangelize the product
Try traditional PR to improve download rates and a bevy of quality content regarding the site
Use event tracking and some iteration of “last state” tracking to prevent users from bouncing
Use open graph (wisely!) to help spread the word.
Make an absolutely killer app (if you’ve done that, feel free to ignore most of the above).