Select "Extras" from the Main Menu and go to "Cheats"
Right, Right, Left, Down, Up, Up, Up, Down - Unlock Body Surf Ability.
First you must unlock the Kill Event called "Rolling Thunder," which appears between the East Village and the Lower East Side (one block from the East coast). Right next to the Event is a Thermobaric Tank.
Jumping into it will activate the Event, but you can back out of it before the Event begins. Do this correctly and you'll have a free tank.
Note: If you exit the tank it or use it to destroy a Hive or Base it will vanish. You can grab it again at the Event point.
To unlock the extremely difficult Platinum events, earn Gold in every event. There are also Radical events to unlock which are almost impossible.
Mind the Crows:
Infected water towers are always circled by squawking crows. This makes it easier to track them down
Unlimited EP Exploit:
On mission 22/31, where you get the first cell phone cut scene, you'll be asked to jack a Black ops helicopter. Once you have the helicopter, you are prompted to pick up a few Black Ops guys and then destroy a Hive. Do not destroy the Hive!
You now have a helicopter with unlimited missiles, no time limit, and as long as you don't destroy the Hive, you can blow up anything else without it kicking off the alert meter. This also allows you to get out of the helicopter without it ending the mission (useful for collect Memory Strands).
The easiest way to get EP in this is to switch to your Infected Vision and fly around blowing up infected water towers. You can save your game in the middle of this mission if you need a break and do the same thing. You can max out your skills and then some using this exploit.
Smooth Landing Speed Boost:
After jumping, avoid using both of your dashes while airborne and save one to use just before landing. If timed correctly, you should hit the ground at near full speed, which is very useful when attempting to evade the military or during a timed activity. Note: This doesn't work for the highest of drops.
To do this trick you will need the ability to Jump Kick so that you can fly towards the first helicopter of The Strike team. You can also use the Whipfist's Grab upgrade to latch onto an enemy helicopter. Double Jump can also be useful. To start, jump up and Jump Kick or use the Whipfist Grab to latch onto the first helicopter. Do the button event to kill the pilots. Fly up as high as possible and look for the next target. Make sure to use the Lock On ability. Jump out of the current helicopter and Jump Kick towards the next helicopter. You can keep doing this as long as there are helicopters. If you fall, quickly use the Whipfist Grab.
Note: This can be very challenging but if done successfully you can attack numerous helicopters without ever touching the ground.