New Super Mario Bros. Wii/World 1-2

Normal Strategy
Slide down the slope into the two Goombas and move forward to find the pipe to the main level.

Now as you come down, you'll see a Goomba, a ? box, and some coins. The ? Box will contain an Ice Flower if you're Super/Otherwise. There's a sign that points right, and there's moving crystal platforms. You will see the first Star Coin soon. Try to jump into it, and if that doesn't work, try using a few wall jumps to get it.

After this, proceed through the level. You will come across Piranha Plants, be careful when jumping over them. Once you have gotten to a certain point, you'll find a place where there's a ? box, and a platform with a gear on it. Jump on the platform, and you'll notice it turn red (if you're using Mario). You can turn the like you're holding a board on opposite ends, and modify what way the platform turns. Now, the ? box has an Ice Flower in it as well. After that, tilt so you have access to the pipe on the upper right of the platform. Jump off the platform, then enter the pipe.

Once you're in this room, there should be a block in the middle, some coins, a Goomba in a box made of blocks, and a yellow pipe on the right. Now, don't collect the coins. This is a very important part. Instead, hit the block in the middle. A P Switch should come out. Get on the P switch, and the coins you didn't get should now be bricks. You want to get up as quickly as possible, and grab the second star coin. Once you've got it, you can collect the rest of the coins. Head back to the bottom of the room and exit through the yellow pipe.

You will encounter a giant blockade of blocks, and some breakable blocks down below. First, you want to break the blocks below with a ground pound, and travel under the main course. The trip is short, and you will find a block at the end. If you hit it, a Star will come out. But be careful, the star can escape, and if you get careless with the star, you can fall down.

The Midway point is right next to the star block, so be sure to grab it. Once you have the star, you want to be careful and watch where you're going. Now, once you've killed as many enemies as possible (and hopefully got a few 1-Ups), it's time to ground pound on the blocks that block entrance to the green pipe, under the massive stack of blocks on top. Once you've broken through with a ground pound, enter the pipe.

You should be looking at a room with two Goombas, a yellow pipe, the green pipe you came out of, a POW Block, and some coins. Grab the Pow Block and use it, and the third star coin will drop down from the top of the screen. The Goombas will die, and the other coins will also drop down. Grab your last star coin, and exit from the yellow pipe.

The level is very straightforward from here, but there is one last thing you can do: the 8 Red Coin challenge. You'll encounter one of the motion controlled platforms again, so jump through the red ring and collect all the Coins, and receive your award. From there, just enter the pipe.

You'll come back to the overworld, and you'll find yet another motion controlled platform here. Tilt it with the right point facing up, and then try to get the one up on the flag pole. If you get lower, don't worry, you still reached the goal.

Star Coins

 * 1st Star Coin: Near the beginning of the underground section, in between a regular wall and a crystal wall.
 * 2nd Star Coin: In the upper part of the room accessed by the pipe next to the first motion controlled platform.
 * 3rd Star Coin: In the pipe that you access by ground pounding on certain blocks. This star coin can be seen from the middle (main) underground portion.

Enemies

 * Goomba
 * Koopa Troopa
 * Piranha Plant (Pipe)

Items

 * Super Mushroom
 * Red Coin Ring
 * POW Block
 * Ice Flower
 * Motion Controlled Platform
 * Star