Today i surfed the web searching about guidelines and best practices on writing android apps. In this in-depth search i found some useful slides and tips:
1. Android Ui Design Guidelines
A slideshare with some usefull tips about android ui design:
2. Android Ui Stencil and PSDs
I also found a great resource where there are some other stencils and psds to download.
3. Android icon templatepack
I also noticed the Google Android team released the icon template pack so you can easily design you’r own menus and icons using their psd with a lot of presets.