Many people aren't playing Dead Ops as much as the other zombie maps. I feel the community isn't comfortable with the game type. I am going to make this guide for beginners to get comfortable with Dead Ops. Feel free to edit.
1. Always keep your distance from the zombies. This game acts like Geometry Wars. If you get touched by a zombie you lose a life and a good amount of cash. If you want to stay number 1 you will learn to try and not get cornered or let to many zombies accumulate on the screen.
2. Power-ups are useful but they have very limited time. When you walk onto the screen you will see at least one power-up like a flamethrower or a chicken. Do not go for these right away. They act the same as the nuke, double points, insta-kill, etc. from regular zombies. They have a limited time before they disapear. When they start to blink you will know they are going to run out. So only use these when the action stars to get hairy or if you are getting near the end of a level.
3. Nukes and speed boost are fun but there is no need to use them right away. Use them when you absolutly need them.
4. Money is how you will survive longer in the game. Pick up as much as you can as fast as you can. These will give you extra lives every 200,000 points.
5.Bonus rooms will pop up from time to time. Pick up all the cash as fast as you can but wait until you have got all of the money to pick up the power-ups.
Remember these tips and you will improve. Have fun!