There are apps on the Store that claim to help you increase battery life. My experience says that's a big lie. It just boils down to your usage, settings and generally being aware of what your machine is running. There are a couple settings you can use, e.g. Wi-fi timer (only run wi-fi when you're using it), screen brightness (this can be a huge energy guzzler), media-server (especially on the Samsung Galaxy S3), background sync, GPS, etc. There are apps like Task that may show you what you're but they really don't save your battery.