Bring a Super Bell in reserves for this level, it makes things simpler. Start off by jumping atop the second set of ? Blocks to find a Fire Flower that you’ll want to switch to your reserves, using the Cat Power-Up now. Continue moving right, taking the steps up and climbing the wall to reach a Green +Clock high above. Leap down and jump into the painting to reach a room full of Peepas. Leap over them and try to stay to the left so you can grab Green Star #1 with about 2 seconds left on the timer.
When you leave this room ride the nearby sofa upwards to the Stamp then proceed through the door at the end of the hallway. There are a bunch of bookcases in this area, but also a bunch of Boos. In this library you’ll need to hit all the bookcases in the back to slide them out of the way, revealing Green Star #2 . Head right to the Checkpoint Flag and if you leap against the back wall you can reach another Fire Flower if you need it.
Continue heading right to find a Big Boo, then check the mirror to notice there’s a 1-Up Mushroom at the screen side – you can reach it by walking onto the cloudy platforms. Go up the steps, ignoring the fake green pipe. At the split go left if you want to grab a Green +Clock but otherwise go right. You can make a leap out to the cloudy platforms past the door for some coins but it’s not worth the time. Through the door, you’ll end up outside where the entire section is filled with Boos and fake items. Just rush past everything to the next door to return inside. Claim the Green +Clock to the left for a bonus 100 seconds then dash all the way right to the sofa. Ride it to the second level and use the pipe to spawn Green Star #3.
Jump down and enter the door to reach the Goal Pole, but the first one is a fake!