The steps to Success are:
1. Begin with the end in mind
2. Understand how your app will be used
3. Clearly document your app before it's built
4. Document your distribution strategy
5. Research and research the developer
6. Test the application before and after distribution
7. Perform a post-mortem
Once you've developed a clear app document, you're going to need a developer. If you already have an in-house developer, then you're work is done - give them the document you have and guide them through the project. If you're running a lean operation, then you'll need to find a developer to do the work for you. With the search for a developer, you want to make sure they provide for you a clear path to the end result, including the distribution. There are plenty of iphone apps development toolsets that allow you to 'do most' of the development work yourself using App hybridization. These work great for many apps. You'll have to research the offerings thoroughly to be sure you find your best fit. Don't fall victim to the "cheapest" on the development side if you find that the ongoing support or even the distribution help is non-existent.