As you start the level you’ll notice that the screen will be scrolling so you need to keep up. Hop over the first fence and hit the ? Block for the Super Bell. You will want the Cat Power-Up for this level, it makes things simpler and is required to claim some of the items. Continue right past the enemies to a Coin ? Block that allows unlimited coins, just watch out for the fence that sweeps across. Ahead you can obtain another Super Bell if you hit the hidden block above the brown ones.
You’ll approach a somewhat trickier area now with a few moving fences. After the first leap you can spot Green Star #1 so climb up or wall jump to claim it.
There are some Donut Blocks that will disappear if you stand on them for too long but it’s the only safe way across without a Power-Up; with the Cat Power-Up simply do a mid-air pounce and you’ll glide gracefully to the Warp Box. Before taking the Warp Box, realize that the screen stops scrolling for a moment and make a leap past the fences to Green Star #2 at your right.
Through the Warp Box you find the Checkpoint Flag , but you can’t take a breather yet. Defeat the Biddybuds then snag the Super Bell as you climb up then across a string of Donut Blocks. As the screen moves up you’ll find a fence with a clear pipe nearby, don’t use the pipe! Instead, climb up the fence to find the Stamp and a Cat Wheel. Hit the Cat Wheel repeatedly to raise the platform to your right then time your run and climb up to easily claim Green Star #3 .
From here you need to be patient and leap over the fences, past the Biddybuds, and over to the Warp Box. Hit the Cat Wheel in the Goal Pole area to raise a platform that makes it possible to leap to the top, but with the Cat Suit you can just make a half-way jump since you’ll climb to the top anyways.