Jailbreak stuff:
If you are using Winterboard, practice minimalism. Use themes that aren’t heavy-loading. Some themes are so delicious-looking, yes, but you have to exercise restraint for the sake of performance.
Tweak settings in themes and mods and widgets so they don’t fetch data frequently. If IntelliscreenX checks FB/Twitter every 30 mins, try increasing it to every hour or so.
Test Lockscreen themes carefully before deciding on the one you want to use. Many minimalistic LS themes consume battery too (from personal experience).
Constantly tweak and test till you figure out what’s eating the battery and what’s not.
This is largely based on trials and errors.