On the second floor, there is a couch. Jump on it, but dont jump. Wait until the guy walks toward the edge and then jump. Then go left and enter her lair.
There are no snowballs on Counterfeit Island. (see the related question)
Stay on the bottom level until you get to the left side, and the jump up on the boxes behind a guard. Then, if you time it right, you can jump to the third level, sneak past the guard, and onto a very bouncy couch. Then you use the Black Widow Card Key, to get into the locked door!
You have to get a balloon.
you have to take the underground tour
In the Black Widow's lair, you can get past the guards by going along the bottom, then climbing up above and behind the second level guard. When you see the female guard on the third level turn around, follow her and jump onto the springy chair. This will bounce you up and left to the Key Card door.
You hide behind the furniture.
To get past the guards, go all the way to the left, climb above the boxes to avoid the male guard, and when you see the (female) guard on the third level, follow her and bounce up on the sofa to the locked door. (Use the key card to open the door)
If on Counterfeit Island, hide behind the plants and statues.
you go behind the furniture and statues
look up the walkthrough on youtube its so easy.
You go to the scream and hang above it
To get past Black Widow's guards (after you get untied), go to the far left along the bottom. Climb up above the guard on the second level, and wait for the female guard on the third level to stop and turn. When she walks away, follow her, and jump onto the springy chair to reach the top level (where you use the keycard).