The Beep Blocks in this level go off every second, so you won’t be able to dawdle on any of them for more than a brief moment. Cross the first set of Beep Blocks and hit the ?-Block for a power-up (Super Leaf), which will be extremely useful in this level. Continue along past the next set of blocks, where you will see a Mario character switch. Unlike the other ones you’ve encountered in your playthrough, this one will just make some coins appear, so you don’t need to use Mario here. When you reach the bigger area with a bunch of Beep Blocks, you should see Green Star #1 floating above a ?-Block.
If you have the Tanooki Suit, you should be able to get a good running start and float over to it. If not, then you have to time your way across the Beep Blocks and grab it when you can. Once you do, take the Warp Box to the next area, where things get a little bit more complicated. You will need to climb up a set of alternating Beep Blocks, while trying to dodge the one Parabones, as well as a Spike tossing down some spiked rollers. When you do finally make it to the top, you will be blessed with a Checkpoint Flag, as well as a Green Star Ring. Quickly grab all of the coins, with the help of some invisible cloud platforms, to get Green Star #2.
Cross down the other of where you climbed up, using the Warp Box to go to the next area. The ?-Block on the far side will have a power-up, then you will need to slide down the hill of doom. The Beep Blocks will still be changing back and forth very quickly, so you might need a few lives in order to get the timing/pattern down correctly. About halfway down the narrower section, you will find Green Star #3. When you finally manage to reach the bottom, use the Beep Blocks to get the top of the Goal Pole.