Instructions
Form a team of players who will run with you for the long haul. Those who choose to go it alone for all 65 levels put themselves at a disadvantage. Players who team together and practice strategies for the game will rack up experience points much more quickly than any one person can do alone. Get your friends to play with you or make new friends online.
Master two or three maps. You will receive experience points towards leveling no matter which map you are playing on. Someone who wins repeatedly on the same map will level much faster than someone who loses a match because they are playing on a map they don't know as well. Playing the same map can get boring, but helps you level to 65 more easily. You can have fun and play the other maps once you reach maximum level.
Equip your new weapons and gear. As you and your team level through the game, you will unlock new gear and weapons that can make your character stronger. Always equip the new items as soon as they are unlocked.
Avoid secondary objectives. Each map will have a list of various things you can accomplish in the level. Your main objective is to kill the other team as many times as you need to win the match. If you want to get to level 65, focus on killing your opponents and winning the match. Secondary objectives like Xbox Live achievements can wait until you reach the maximum level.
Grind. To be honest, a game like "Call of Duty: World at War" takes time to master. You won't get to level 65 overnight. Plan out time with your teammates in which everyone can be online. Schedule a few hours of time and just grind experience points.