During the"Welcome To The Jungle" level, just after getting the first Nanosuit upgrade, enter the jungle and equip the Predator Bow with explosive tipped arrows. Quickly cloak and use the low draw strength to shoot your bow at the buck directly in front of you.
In the "Gods And Monsters" level proceed to the checkpoint before entering the Ceph wormhole at the end of the level, before the final Boss. Your Nanosuit will become supercharged and enemies will start spawning. Go back through the large alien area and keep killing the enemies until ten are killed with one supercharged shot.
During the "Post-Human" level, proceed until you leave the computer room and enter a large open area. Follow the catwalks to walkways with CELL soldiers, then fight the soldiers and kill as many as possible so they call for a helicopter to back them up. You will see its searchlight on the right side of the main causeway when it arrives, then use the Predator Bow with the strongest draw to get the best range and accuracy for your arrow. Choose the explosive or electric arrow and take down the helicopter in one shot.
During the "The Root Of All Evil" level, proceed until you leave a cave into a large open area, with a fallen tree at the cave's exit. Look to the left just to find a tan donut-like life raft on the shore of the river. Interact with it to push the life raft into the water, then jump on it and ride it on the river. Crouch to avoid getting knocked off.