If there was one lesson from this week's App Developers Conference discussion on app monetisation, it was to think about how your app will make money before you finish creating it.

"Designing your app with advertising in mind is the best way to go," said Eros Resmini, SVP marketing and developer relations at OpenFeint.

"Just slapping a banner at the bottom of your app six months in is not the way."

Resmini joined TapJoy president and CEO Mihir Shah, Lolapps CEO Arjun Sethi, and Millennial Media SVP global monetisation solutions Jeff Tennery for the panel Monetisation Revenue Models: Premium, Free or In-App.

Pick your model

While the panel agreed that ads are becoming a more important revenue stream for app developers, the conversation got heated when it came down to if premium should be considered by indies.

"When it comes to premium, strong brands do well on iOS and Android, like EA Sports," Shah said.

"With new brands, we see 10x to 20x more downloads when they're free... If you don't have a known brand, it's tough work."

Premium doesn't automatically mean profitable, even with big brands, Resmini argued.

"I'm skeptical EA is making its money back... It does the $5.99 premium price, but always offers a discount to get the users.

"On the other hand, look at the 99c guys, like [Bolt Creative's] Pocket God, [Lima Sky's] Doodle Jump, or even our friends [Rovio with] Angry Birds."

It's the indie idea of quality content combined with low price that's driving the market. 

What works best

In the end, the panel agreed, your revenue model has to fit your product.

"Video interstitials work with [Zynga's] Words With Friends. They know their audience," Tennery said.

"You have to look at what works for a particular app. There is no one solution."