Extra Arrow at the beginning of the Ship
Right after the cut scene where the main character tells Henry he has arrived at the ship, walk to the end of the ramp leading on board. Do not step on the ship yet! From the edge of the boarding platform you should be able to see a man standing around a corner straight ahead Simply pull out your bow, take aim, and kill him. Now step on the ship and deal with what happens. When you can relax again you should have an arrow in the guy you killed, and one sticking out of the tank in the middle of the area you are in, along with another goody that guy will drop.
Complete each achievement to get the allotted gamerscore.
Do it once (20) - Finish the game once(any difficulty mode)
Elevator repair service (10) - Repair the elevator to rescue the people stuck in the Fireworks episode
Fifth quick kill (10) - Perform 5 Machete quick kills while being bullied
First Machete quick kill (5) - Perform your first Quick machete kill while being bullied
Five victims helped (20) - Help or rescue 5 victims
Machete quick kill, the third (5) - Perform 3 Machete quick kills while being bullied
My first rescue (5) - Help or rescue your first victim
Some tomatoes for her (10) - Provide tomatoes to the hungry lady in the foggy streets
Survivor (40) - Finish game in Survivor mode
Ten victims helped (20) - Ten victims helped
Three victims helped (15) - Help or rescue 3 victims
Ultimate rescuer (40) - Rescue / help all victims in the game