Firstly, the app you are posting has to be free, or have a free/lite version of the app available and presented in the thread as well.
Second, please only make one thread about your app. When an update for the app is released, announce it in your previous thread.
Thirdly, screenshots of the app are highly recommended when you promote you app here, as it will bring more attention. Pictures are almost always nice to look at, and give a community member an idea of what to expect.
Finally, make sure you are willing to take constructive feedback about your app. It is my belief that through working together, we can continue to make the Android community (and its apps) better than any other platform.