Lieutenant JG Difficulty:
Beat the game with using Ensign difficulty

Lieutenant Difficulty:
Beat the game with using Lieutenant JG difficulty

Lieutenant Commander Difficulty:
Beat the game with using Lieutenant difficulty

Commander Difficulty:
Beat the game with using Lieutenant Commander difficulty

Captain Difficulty:
Beat the game with using Commander difficulty

Rear Admiral Difficulty:
Beat the game with using Captain difficulty

Admiral Difficulty:
Beat the game with using Rear Admiral difficulty

Get multiple Grenade launcher:
Finish the game 3 times

Terrorists Weapons:
Beat the game ranked "ensign" and unlock terrorist weapons in armory.

Multiple Grenade Launcher:
"Bravo open/close door"(when close to a door--point at it with the crosshairs) "Hand up,get down" (sneak up to guards and yell it) "Breech,Bang,Clear"(clear a room by pointing crosshairs into it-your team will throw in two bang, grenades, and a frag) "Bravo diffuse bomb" (when pointing crosshairs at bomb) "Team low profile"(team sneaks around killing terrorists stealthy) "I got a gun!What do you got?"

Easy Kills:
In level 4 go prone and go under the huts and blow wholes in the floor. The enemy wont no what hit'em.
P.S. Throw a flash bang or a smoker in the window first.
P.S.S. When more enemies come after the final hut throw frags way out behind the hut while your still on it, then kill anyone who charges, then crouch and move silently around the perimeter of the back of the island and kill the surviving snipers.

Defuse The Bombs:
In the third level you must defuse 3 bombs in the alloted time.To make things easier disarm the to bombs close together to the north east.Then kill terrorist leader in building C.This will reset the clock.Then go for the last bomb.By the way each bomb takes a little under 30 seconds to defuse.Good Luck Commander.

MR. Pickle LEVEL:
If you want to know how to beat the level when you have to rescue Mr. Pickle, listen up. You do not have to be stealthy on this level. I armed my fire team with M60's,A silenced pistol,frags and extra ammo.When you starty the level there are 2 tangos around the rock i think you know what to do. Then the alarm might go off. if not run to the beging of the bridge i know you would want to take the path under the bridge.but just go to the end of the bridge there will be an enemy at the top of the front gate take him out,then there will be an enemy a few more enemys in the arean kill them then go to the entrance of the compound on the way there take out the gaurd towers.i know that the alarm will be going off so tell bravo to hold at the entrance do not let them enter. then go set a sachtel charge done by charlie out side of the compound. when you set it tell bravo to enter the compund then you go enter. wait a minute and take out all enemys. make sure you get them all c!
ause there are 2 with MGL'S. then disable the genorater.there will be a sniper tower just next to yuo take it out.then there are 2 buildings to the right of the tower follow the wall the last building clear out the building there are 2 tangos on the 1st floor and 1-3 on the second floor the map should be on a table on the 2nd floor. take it.then go rescue MR. Pickle. tell Bravo to frag and clear the building then tell them to wait outside of the door so you don't run into any uninvited guests.when you rescue him tell
Bravo to attack to foxtrot. remember the sachtel yuo set run out of the compound from the hole you made.with Mr.Pickle.then go meet up with Bravo Element. tell them to follow you to the extraction zone.

Refill your clip without reloading:
Once you kill somebody and you only have a few bullets in your clip,switch weapons with the guy you just killed and switch back, your clip is full without the cost of one clip.

Hide in plain sight:
1.Always stay in the prone position(crawl).
2.Use the surrounding foliage(trees, grass, etc.)as cover. Remember the thicker the better.
3.With all these steps in mind, plus camos, the enemy should just stroll right past you.

(HINT: These tips work better with online play. The single player enemy AI is smarter than an actual human.)

More Weapons & Smarter A.I.:
Beat the all 12 missions to get more weapons,i.e Desert Eagle, Uzi, and Grenade Launcher.
The enemies will also be smarter and better shots.
The more you play through the higher your rank will be, plus more weapons and more intelligent enemies.

Headset Commands:
"Bravo open/close door" (when close to a door -- point at it with the crosshairs)
"Hands up, get down" (sneak up to guards and yell it)
"Bravo diffuse bomb" (when pointing crosshairs at bomb)
"Breech, Bang, Clear" (clear a room by pointing crosshairs into it - your team will throw in two bang, grenades, and a frag)
"Team low profile" (team sneaks around killing terrorists stealthy)
"I got a gun! What do you got?"

Hint: Mission 2:
At the beginning, tell your men to hold their position and go to the right, up the hill. Stay to the left side of the hill while ascending it. You will see an enemy fairly soon in the mission. Quietly and carefully snipe him. There will be another one very shortly after the one you just killed. Continue on the cliff and you will reach a drop off to another cliff. Jump down. Walk slowly to the edge or close to it until you can see the small cabin. Snipe the man standing outside quickly with one or two shots. Then, tell your men to regroup after you jump down from the cliff and go to the cabin. There will be one or two men inside -- kill them quickly. Keep moving north -- that is where all the action is located.

Objective 1: You will find the Intel in the big place with the bridge-type object on the third floor. It is in the laptop.
Objective 2: The weapon caches are the boxes stacked on top of each other. Put C4 on those and that will do the job.
Objective 3: As one of the secondary objectives, blow up the generator with C4 as well.