The one thing I found to destroy my battery life and even drain the battery to the point it wouldn't turn on, not even for it to shut itself down again was leaving Best WiFi Performance checked.
Go to: MENU>SETTINGS>WIRELESS AND NETWORKS>WIFI SETTINGS>MENU BUTTON>ADVANCED
Uncheck it if its checked and also set your wifi sleep policy to: Every 15 Minutes.
As far as security software goes the best thing to do would be to check the link supplied by El P and understand your permissions and to use your common sense before installing things. The permissions page should not be skipped the same way you would an EULA when installing some software. Using apps to do this is just going to drain more resources. Just watch out for Tetris wanting access to SMS/MMS/DIALER things out of the ordinary etc.
Accepting without looking could result in you being in a situation like this:
Oh and bin juice defender...ain't worth the bother.