New Super Mario Bros.: 7-3

This level starts off on a grassy plain with a couple of Wigglers wandering around. Pick up and item and head down the green pipe on the right. This will lead to a new area, where a giant Wiggler is the level. He'll be taking you to the pipe at the end. I recommend standing near the middle of the Wiggler. He'll periodically hop so you can reach higher places. There's some Red Coins to get, as well as platforms to hop on. Soon, you'll come across an overhead pipe that spews an infinite amount of Goombas. The first Star Coin is over a Boomerang Bro. The next item block you come across will be a Starman. This is no ordinary Starman: this will make a trail of Silver Coins wherever you go. All other item blocks will also contain Starman as long as you're invincible when you hit the block, allowing you to have a ton of fun. The second Star Coin is over a high platform. Eventually, you'll reach the pipe at the end, which is guarded by another Boomerang Bro. Don't try to follow the Wigger offscreen. There will be stairs made of bricks down to the flag. Before you go to the flagpole, pound the top brick to send a vine down, break the lower brick blocks, walk under the stairs, and drop down the gap. The third Star Coin is in an alcove to the right. Use the vine to reach it, then go to the goal.