1) camera problem
fix:switch of usb debugging and install appkiller from play store.switch off everything in developement options and close all background processes
cause: the camera cant take too many background processes and kindly switch off usb debugging.
fix: install recommended gapps by quarx.dont install anyother gapps. if u wish to do so, install the ones for cm 11.
3)apps are continously crashing
fix: for some devices rooting and flashing may be too much for it to take. the solution is simple just flash it back to froyo and back to kitkat.
4)battery problem:install appkiller and close back ground processes and dont open apps for no reason. if you keep it like that the battery drains easily. and also check your battery whether it has swelled or has damages.
these are the most commonly faced problems .try doing the above steps . press the thanks meter if i helped