With smartphone penetration rising and more and more consumers turning to the mobile web, the opportunity to get your mobile app into the hands of those consumers might seem to be growing by leaps and bounds.

But getting the users you acquire to stick around is proving challenging — perhaps even more challenging than on the web.

As the CTO of CBS Interactive, Peter Yared, recently pointed out in a blog post, mobile analytics provider Flurry has found that iOS and Android apps typically retain just 20% of their users after four months, and a paltry 4% after 12 months. For obvious reasons, this makes building a mobile app that’s successful for the long haul a tall order.

The good news is that maximizing user retention in a mobile app doesn’t require magic. Many of the lessons of the web are applicable, and when a concerted effort is made to keep users around, mobile app developers can beat the odds. 

Here are five rules for doing just that.

Rule #1: KISS.

One of the biggest mistakes businesses, developers and entrepreneurs make when creating mobile apps is that they make their apps too complex. Yes, it’s tempting to think that you can fit a ton of functionality into a mobile app, but the reality is that the best mobile experiences are generally the simplest. Knowing this, it’s typically easier to build a mobile app that users will want to keep using if you keep things simple and do a few things really, really well.

Rule #2: Give users a reason to come back.

It should go without saying but the more you can do to make using your app an attractive proposition, the better off you’ll be. Fortunately, there are numerous ways to encourage frequent use. Obviously, what’s appropriate will depend on the nature of your app, but there are plenty of ways to keep users engaged. For instance, push messaging solutions like Urban Airship make it easy to provide push notifications, while ad networks like Kiip can provide users with ‘rewards’ for their in-app accomplishments.

Rule #3: Focus on building solutions, not apps.

If you’re focused on building an app so that you can cash in on a flurry of 99 cent purchases or mobile ads, it’s easy to fall into the type of ‘gold rush’ mentality that emphasizes getting rich quick over creating lasting value. The better approach: build something that solves a painful problem and apply mobile to your solution in a useful way. In the end, you’ll be far more likely to build something valuable enough to produce repeat use.

Rule #4: Remember that mobile is just another channel.

It may seem like mobile is where the action is at, but don’t fall into the trap of believing that mobile apps are the end all and be all of delivering information and functionality today. We live in a multi-channel world and although mobile has fast become one of the most important channels in many industries, it’s not the only channel.

Assuming you’ve followed Rule #3 and built a solution, it’s important to evaluate other channels through which your users would want your solution delivered. Chances are there are multiple channels of value, and by making your solution available through them in a thoughtful, integrated way, you can build long-lasting relationships with users through multiple touch points.

Rule #5: Be trustworthy.

In the age of the acquihire, users are increasingly finding that the services they love can be shut down in an instant – even if the startups behind them are well-financed and/or apparently successful. Recently, for instance, there was a lot of discussion when Digg founder Kevin Rose shuttered his latest company’s first mobile app, Oink. As it turned out, the death of Oink was the result of Google acquihiring Rose and part of his team.

It’s not clear whether the growing number of ‘disappearing startups’ will destroy the willingness of mainstream users to try new services, but certainly they can’t help. So if you’re building a mobile app and want users to invest their time in using it, it certainly can’t hurt to persuade them that you’re invested in it too.