The key is to know what is using your power. Then you can see what you can do to address it.
I suggest installing GSam Battery Monitor. Let it run for a full cycle, then open GSam and see which apps are using most power. There are a lot of options for giving detailed diagnostics in that app. If you are running down fast when you should be in standby, it's worth clicking on the app usage then looking to see what is keeping the phone awake (Wakelock Detector is also useful for this).