Before going further, plesae note that you'll have to pay 25USD for a Google developer account in order to publish apps for the Android Market. For the iPhone AppStore (iTunes), it's even more expensive, 99$ a year minimum I think.Now for your question:The most easy way to develop an Android app is through the Google (Android) AppInventor since you virtually draw the application and graphically organize its actions and the dependencies between the screens. It's kind of like in Visual Basic if you know that already. Anyway, even if you have no experience, AppInventor is really a good way to start, it includes an emulator, and it's free of course. However, in order to package it in an .apk (to run it on a phone) or to publish on the market, it's not a straightforward step but it's possible anyway through PhoneGap for instance.Further step would be using JavaScript programming through a platform like Appcelerator Titanium. They have developed a bridge between JavaScript and both Obj-C (iOS: iPhone/iPad) and Java (Android). So the good thing, is once you compile the app, it's usable for both iPhone/iPad and Android phones/tablets. Titanium includes emulators for all those platforms. In addition, it allows to package even for MacOS X (Apple computers) but you have to pay something for Apple, again.Unless you already know and master Java, in that case go directly with Eclipse IDE and hard code.