Avoid CPU intensive applications, dim your screen, put your tablet / phone in stand by when you are not using it or background downloading an application, if you are using an application that does not require wifi, such as a game like Angry Birds or mupen 64 plus disable it if you're listening to music , turn down the volume just a little bit. All these things should increase your battery life hope that helped update 11 -3- 15 though I've never actually tried custom roms I read and seen on YouTube that some custom ROMs like the highly popular CyanogenMod have loads of battery saving features.
I wish you the best.
Sent from my SM-T310 using XDA Premium HD app