I am a firm believer in the ability that people can make everything they set their mind to. I love those do it yourself books and have done many things by myself. And yes, it can be a great way to do something productive with your free time and on top of that you get more skilled and you don’t need to pay anything. But everyone has some sort of limits. If you are short on time, lack motivation or simply you are all thumbs you still might need a professional. Another instance when is better to use someone professional and skilled person is when you are faced with changing market. For example if you have an idea for an android app you cannot simply buy a book “developing for dummies” and hope for the best. The app market is changing so fast that an idea will soon get obsolete or simply someone else will think of it. It is all about the need and the speed to react on it.
The decision on which platform to target can be yours. This is nothing complicated, see the targeted groups and try to get reasonable statistics of which platform they are using. The two most used mobile platforms are the apple’s iOS and google’s android. But if you are looking for other more serious audiences don’t overlook Blackberry and Windows mobile.
After the decision on the platform is made, the only thing left to do is to hire mobile app developers to help with your app idea. Note that in order your app to sell you will need superb stability, great graphics and support. If you can, find someone that will offer all of this. In the end, you will get your app rated and approve and the money making can start.