I had the same problem with Xperia P. Finally i found out some solution which helped me, hope they help you.
1: Weather widget consumes a lot of battery power.
2: WiFi, Bluetooth, GPS, NFC, radio, should not be powered ON unnecessarily.
3: Remove McAfee (make sure you didn't set password in some earlier days, in this case you must remember your password otherwise your phone will be locked or you must have your another mobile no: that you might have provided to McAfee and for this your must have some credit in your SIM)
4: Go launcher consumes more battery therefore i would recommend APEX launcher
5: Don't let your mobile to consume full battery till 0%