To pass the 2nd forgery test, look at the lower right side of all three paintings. You will see that one of the three signatures is different from the other two. (You do not have to pick which one.)
(see related question)
There are no snowballs on Counterfeit Island. (see the related question)
You have to get a balloon.
you have to take the underground tour
You hide behind the furniture.
you go behind the furniture and statues
If on Counterfeit Island, hide behind the plants and statues.
You go to the scream and hang above it
look up the walkthrough on youtube its so easy.
you cant its part of the island mission
Just run past the window when the guard's shadow isn't visible on the shades.
when you enter the island, keep going left, past the museum. then click on the sign that says "city docks".
its at the place where you take a tour. right past the clown store.