His tips in short: 

• Be absolutely meticulous
• Add some fun touches
• Consciously social
• Go big on the launch
• Don’t depend solely on domestic sales
• Listen to feedback and keep improving

Taptaptap’s Camera+ app sold in huge numbers in the US initially but then shifted to mostly international sales after a while. If you’re making an iPhone app, do not underestimate international market and make sure your app is not only worth using but also a joy to use.

John Casasanta shares tips on launching non-game iPhone apps