Intermittent starting problem

My car is having intermittent starting problems. Every so often engine wont fire but will more than likely start on next crank, im thinking its a fuel or electrical problem, ive renewed plugs and fuel filter but its still happening. Im wondering could it be fuel pressure regulator or maybe the coil. Is there anyway I can test these or else im going to have to renew one thing at a time which is gonna be expensive.