One of my strategies about waging war is to build up your military strength over time, and chose your targets from smallest to largest of your rivals. Once you have the technological lead, you wait until you have won a time victory, then you can forget about not winning because of war anger. Then you make your move on the target civilization, declare war, then move your troops in. they will be completely unprepared and you will have the advantage. Then once you have wiped them off the face of the earth, time for the next one!
