Paper Mario: The Thousand-Year Door Tips

Hidden boxes
Throughout the game there are invisible boxes that could hold items, coins, or badges. Here are the ones that I know of.

Creepy Steeple stairs - 1 coin
Under shine sprite in Glitzville - nothing

When you first see a Punie, go straight down from the hole, to the wall and jump - Badge

In Fahr Outpost in the area with the pipe, jump in front of the trees until a box apears - Badge

In Boggly Wood, in the area that you have to push the blue button to raise the airplane panel, go to the button spot and about half way down keep on jumping until a box appears - Badge.