As mobile's influence on digital marketing continues to climb, mobile apps are playing a more central role in marketing, specifically in the mobile app install ads category.

In fact, according to eMarketer research from last year app install ads were expected to reach $3 billion in 2015, accounting for 10.4% of mobile ad dollars and representing an 80% year-over-year increase. And per app analytics and marketing intelligence firm App Annie, the global app market is expected to increase 24% to $51 billion in revenue this year across all app stores, and app store revenue is slated to hit $101 billion by 2020.

"Mobile app install ads have become the key to getting in front of the right audiences at the right time, and building an audience," Sean Galligan, vice president and industry lead for entertainment at Yahoo, told Marketing Dive in October.

But even though apps are helping marketers with real-time messaging and many companies – from many industries outside of the traditional gaming companies such as retailers, banks and media firms – now have apps, questions around the health of the app economy and how to best integrate apps into overall marketing strategies still come up. That, and what to track when marketing a new app.

And marketers could be doing more to maximize the benefit of having developed and launched an app, Nancy Hua, CEO of mobile A/B testing service Apptimize, told Marketing Dive. She said there are five key points to track when marketing an app (more on this below) to ensure its success from launch.

"This is a quickly growing and developing industry," she said. "The 'experts' don't have it figured out because everything is changing so fast. You can be the expert even if you're not a developer. You just need the right mindset to go out there and experiment and learn."

App success begins at the launch

One key mistake marketers make with new apps is focusing on gaining users and not improving the app itself, Hua explained. Apptimize sees a lot of app makers allocating a good amount of time and resources upfront to creating the app, and then investing a lot of money on amassing users, but let iterating and tweaking the app fall by the wayside after launch. 

"You're not going to get everything right the first time, so you have to have a plan for how you'll improve the app as you start to get user feedback and analytics," Hua said.

That said, tools exist that allow marketers to improve apps without having to tap back into engineering resources. According to Hua, ad campaigns can test messaging, run in-app promotions or do A/B testing to optimize apps on the fly.

Though A/B testing does most likely require a third-party solution since Apple and Google don’t currently enable A/B testing, Hua recommended finding a tool that is designed for non-engineers so tests can be run without developers. Testing should be controllable without waiting for approvals from Google or Apple.

A major reason to begin optimizing the app experience from launch, according to Hua, is there’s a danger of spending an entire budget on bringing in users who will have a terrible experience.

"Marketers should spend just enough to get some basic ideas on what needs improvement within the app, quickly fix those issues, then spend more on acquisition... rinse and repeat," she explained.

As far as utilizing the popular app install ad format, Hua said those campaigns are great for testing out messaging, but that there is a specific strategy that will give marketers the most benefit from the ads.

"Don't dump a lot of money into acquisition on a rough first launch," she cautioned. "Spend some money to get early users, learn, iterate, spend some more."

The goal should be to get 30-day retention rates up and users leaving positive reviews. At this point marketers can begin leveraging both paid and unpaid tactics to ramp up the user base. Install ads are good to keep in the marketing mix because the ROI is easy to measure and the paid marketing can have a positive impact on organic traffic, Hua explained.

What to track once you have an app to market

1. The purchase funnel

"You not only need to be measuring every single step of the way, but also set up A/B tests to question the entire structure of the flow and conventional wisdom," she said. This means from how many people are in the landing app and what percentage of items viewed lead to the checkout button, to how many people click on the next button after the checkout and eventually add a credit card. 

A case study on how HotelTonight increased checkout by 26% by getting rid of user accounts, she said, is a good example of how accurately measuring from the start can help propel your success.

"How many finalize 'checkout'?," she said, is the question you need to keep top of mind.

2. Influence metrics

If you know that your clients are making purchases elsewhere, for example on the web store, then it's important to be tracking influence metrics, like how many items viewed per visit, across channels.

"What most apps do is track the number of items someone views the details," she said. "Either they click on the thumbnail that appears on search results or they tap a 'details' button that shows that they are actually interested in that offer and not just glancing through."

That being said, Hua cautioned, it's important to remember that "40% of adults start activity in one platform and complete it on another."

3. Onboarding experience

"You must measure the quality of your onboarding experience. If you don't nail onboarding, the rest of your app doesn't even matter because no one sees it," Hua explained.

She said there are several metrics that come into play here.

"Depending on how your app is set up, you'll want to measure the number of people who have signed up or done some sort of action that indicates interest in your app. Maybe you've seen that customers who browse through five items are much more likely to become long term users of your app," she said.

According to Hua, most apps will need to set up some sort of "x-day" retention (for example, 7, 15, 30, 60, 90) to measure what percentage of new users come back a second time in an "x" period of time.

"This is a good measure of whether or not your app has done a good job of conveying value right away," Hua said.

4. Engagement

In terms of engagement, this depends on the app. For some apps it might mean a combination of "x-day" retention for new users and number of visits per month, or it could include items viewed per visit. 

"You need to find the engagement metric that works for you, but the point to keep in mind is that mobile is all about engagement," she said. "The whole reason you want to build an app instead of another website is that the mobile app is in your user's pocket all the time."

5. Acquisition spend

Carefully tracking acquisition spend is crucial for all apps, but particularly to newcomers.

"Too many apps spend a ton of money on ads and then only track which ones get clicks. You need to also track which ones actually lead to purchases or an influence metric," she said, adding that either way, a good rule of thumb when it comes to app marketing is to "question everything."