I’ve recently started my first Android project (yay!) and after coming from iOS I know how important using system standard functionality and design is. Users expect your app to work in a certain way and not all iOS stuff will translate directly to Android design and visa-versa. I learned a lot about what users expect on iOS by reading the Human Interface Guidelines (HIG) published by Apple. There isn’t a HIG of sorts published by Google for consideration when developing Android apps. However Mutual Mobile has published an Android Design Guidelines document that has already been very helpful on my new project. If you’re designing for Android and aren’t already familiar with the device standards you should take a look at this document.
Other Official HIG documents: