The default position for your hand should be: hand is parallel to the floor, no fingers are curled, and hand is high in the air.
Picking up an object: To pick up something as large or larger than your hand, make sure the object is below the center of your hand, hold down mouse 1 until you are touching the object, and then press and hold AWERSpace.
Picking up a Knife: To pick up a knife, make sure the object is between the fore finger and the thumb, hold down mouse 1 until you are touching the object, and then press and hold AWERSpace.
Manipulating objects easier: It may help to pick up objects when your hand is slightly rotated to the left from the default position. For example, the hand circular saw may be easier to use when it is at an angle. Same thing goes for the laser.
Stabilizing blood loss: If your patient is bleeding a lot, pick up the green needle and stab him with it. If you pick up the green needle with your hand directly above the needle, you will inject yourself and start to hallucinate. To stop the hallucinations, you must inject yourself with the blue needle. The blue needle is poisonous to the patient..
Preparing for an easier time: The patient doesn't start bleeding until you start hacking away at him. Before you begin, you can clean up your table a little by throwing unnecessary tools on the floor, if you want.
A++: It's all about speed, accuracy of cutting (to prevent unnecessary blood loss), and blood remaining. I don't recommend you try going for these until you've beaten the game.
[A], [W], [E], [R], [spacebar] and mouse