First, consider that failure is a relative term. If you personally create an app and are able to get it to provide some meager supplemental income, that's not a failure if that was your goal. If you're looking for the app to fuel and grow a startup or earn a living from it, that's a different story.
I agree with Nicholas and others that marketing is often grossly underestimated. Whether your app is something people want or not, you're clawing your way into a saturated market.
Lack of user engagement and subsequent retention is another HUGE area of failure. Let's assume you've made an app that people want, you validated the idea, solves a problem, blah, blah, all the stuff you should do before launching an MVP. However, people who install the app are not returning to it. Statistics show only 25% of users return to an app more than once. You've got an extremely short window to hook them and get them to keep opening and using your app. There are tons of great articles on mobile user engagement out there (and I even wrote a book on it, I'll send you a copy if you want--not a shameless plug--will send it to anyone on FD who asks) but here are a few things to always consider when launching an app:
- Personalization: give them a personalized experience--tailor the experience to user location, preferences, behaviors and information you've collected or obtained about them.
- Onboarding: make it so they know what they should/can do and make sure they can interact with the app within milliseconds of opening it. Don't make them think, "what am I supposed to do here?"
- Use push notifications and email wisely. Don't spam your users--but send notifications and emails based on event triggers that are relevant to them. So many apps abuse push and forget about using email entirely. Use them both wisely.
- Embed social networking components--introduce the ability to connect and share in every aspect of your app--this isn't to suggest you should create a social network, but simply use the best components of social networking to augment your user experience in ways that make sense in the context of what people do in your app.
There are lots more--just remember--it's not just
about having a great idea and marketing it well--you have to engage your users. Retention is the key to gaining traction once you get installs--engaged users translate to revenue. A great read on the subject in general is "Hooked: How to Build Habit-Forming Products" by Nir Eyal. Search for it on Amazon.