At the start quickly press Up, Down, Left, Left, Right and you should hear a silly sound.
Bare Person
After you kill the leader of the Irish mobsters in the mission "A Midsummer Night's Massacre", Predator is hanging the leader by his feet. The cool thing about this is the leader doesn't have skin anymore. Predator ripped it off. Predator calls it a "Trophy!!" Its cool!
Bug Hunt
Kill enough aliens to complete the bonus before returning to Mother's chamber.
Combos
There are three types of combos. The first is the combo that always ends with a strong attack. It can be executed by pressing the attack buttons in random order, for example Triangle(2), Circle, Triangle, Circle. The second type of combo is the one that ends with a heavy attack. It is executed by pressing Triangle, Circle, Triangle, Circle, Triangle. The last type is the combo that ends with a light attack, usually an impale, that is followed by tossing the opponent in the air. It is executed by pressing Circle, Triangle, Circle, Triangle, Circle. Combos always contain five strikes, and they end with a heavy attack except for the light combo Circle(5).
Come To Mother
Destroy all four upgraded battle armor in the room where the main lift is.
Dead Man Walking
Locate and open two explosive crates. One is near where the Predator starts the mission, on a rooftop. The second is in a parking lot near where the weapons van is crashed.
Death In The Family
At the top of the mansion's stairs, head past the red curtains and take your new trophy.
Defeating Prototype Ulysses
Approach his back and press Jump when a symbol appears above the Ulysses head. The Predator will jump over the robot and kill it with a single blow. Note: This does not works with the gray Ulysses Prototypes with red lines.
Disabling the Ulysses
Toss a pulse mine at it and jump on it; the Predator will kill it instantly. Note: You cannot attack from this position until the Ulysses falls, except if you use the Plasmacaster. Also, this does not work on the Prototype Ulysses or the Pack 9 Ulysses. The Prototype will just toss you off and the Pack 9 will take minimal damage.
Easy melee attack kills
Use the Wristblades, Glaive, or Maul and lock onto your prey. Approach next to the opponent and start walking around it while giving one blow, walk, give one blow, and walk.
Escape
There is a weapons scientist in a depressed area of the lab. Killing him will fulfill this objective. You may want to do that after using him to unlock the retinal scanner door.
Extinction Event
Stay cloaked and head through the first gate to kill the corrupt police chief.
Hot Time/Old Town
Stealth kill the black ops in the recreation without causing them alarm. Use the Voice-lure to draw them out and get behind them (or snipe them).
If It Bleeds
At the 1-2-3-4 junction where the power core is, the weapon upgrade is on the lower level, where the mines are.
If It Bleeds
Disable the cooling fans in order (from one to four).
In The Flesh
Destroy the computer in the upper levels. It may be a good idea to do this bonus mission during the boss' first phase.
In The Flesh
The upgrade is at the end of one of the very narrow bridges at the edge of the arena.
La Famiglia
On top of the mansion. Atttempt it after disabling all the guns and using the greenhouse on the left side of the mansion as a step-up.
Midsummer Night Massacre
Kill the Irish gang's boss. He is on the first street and easy to locate.
Monster Squad
On the west side of the map, there was one of the lift power boxes inside a small tunnel (on the ground) in the previous stage. The weapon upgrade is in the fire.
Night To Remember
In the museum courtyard where Borgia's lieutenants are, take out all the window snipers.
No Predator Sounds
Use the free camera and moves it down until you can see the Predator from below. If you make any movement (for example, use the War Cry, Voice Mimmicry, or the attack buttons), no sound can be heard. However, if you adjust the free-camera you will hear the sounds again.
Perching
There are special poles and platforms that you can perch the Predator on. They usually show up in Tech Vision. Mostly they are horizontal poles, planks, etc. Jump on one of those and the Predator will perch on top of it, allowing you to stalk your prey or get to a hard to reach rooftop.
Raze The Depot
Near where the Predator starts, there are several enemies in an inaccessible room. One of them is the bonus target. Take him out when the chance arises.
Rescue
Use any of the Borgia security guards to open all the retinal scan doors (the scanner extends, and there is no cut-scene movie). Kill the Juvenile-9 leader being held prisoner to complete this mission.
Sink The Shipment
An entry gate near the shed with the Pulse Mines and Maul has several Les Serviteurs ogling some ex-porn star hookers. Terminate the Serviteur leader (icon over his head). Note that causing any moderate amount of noise or undue attention will cause the enemy to flee from the spot.
Skin Trade
Before taking out all the pimps, terminate eight prostitutes by any means.
Ten Thousand Ways to Die
Locate and activate the three cloaked beacons. Tech view will make them easy to find.
Ten Thousand Ways to Die
There is a weapon upgrade on the side of one of the final buildings (you will be able to see it but cannot reach it (forcefield) until you defeat the upgraded battle armor.
The Machine Men
On the track past where the Machine Men initially started off.
Uncle Sam poster in Dead Men Walking
In the Dead Men Walking level, you can see a poster of Uncle Sam on the sides of the Sanctuary.
Under The Gun
After completing the timed section of the mission, locate three pick-up trucks with weapons on their beds. Destroy all three. Two of the vans are near the multi-tiered parking structure where the Predator started the mission. The last van is parked on the street next to some of the gang cars.
Under The Gun: Cop Gender Change
On the roof where El Hongo walks down a ramp, go towards the first recharge point. There will be a white marker on your map. On the street will be a cop with a marker on his head. Scan him in tech-vision. For his gender scan, it will be a female.
Unlock Alien Hunter
Kill all snipers in the mission A Night to Remember.
Unlock Bad Blood
Destroy the large computer at the start of the mission The New Flesh.
Unlock City Hunter
Kill 50 aliens in the mission Bug Hunt.
Unlock Dark Blade Clan
Ignore the first enemies and kill a man instead on the mission Extinction.
Unlock Jungle Hunter
Kill the Irish boss in the mission Midsummer Night's Massacre.
Unlock Maul Upgrade
Destroy the large computer at the start of the mission The New Flesh.
Unlock Ritual Armor
Destroy the three trucks after following El Hongo. The first truck is by a billboard at the start of the mission. The second truck is in a carpark, and the third truck is at the southeast edge of the level.
Weapon Upgrades
Note: Weapon upgrades are cumulative and you do not need to get them in a particular order to "up your guns". All weapon upgrades are out in the open (never in a box) and are usually just hard to find.
Wristblades Trace
With the Wristblades equipped, stand in front of a wall. Press Light Melee Attack in front of it and quickly move back. A blue trace of the Wristblades will appear, following your arm as you move for a few seconds.