Go to world 1 mini-castle. A little bit after the checkpoint, go into a door with a cross on it. Instead of going into the other door with a cross on it, in the other room, go into the hole in the middle of the wall on the right. There should be a flag somewhere near. Once you land on the flag and have completed it, a path to a cannon should appear. Do the cannon and you should be in world mushroom.
Go to a star house and get a gold flower in your item pocket. Then go to W2-4 and use the random block. If you got a gold flower, good. If you didn't that is o.k. Too. Go to the second hill of pass-through platforms and find a gold pipe next to a Pokey. Go and use the gold flower if you didnt get one earlier. Jump on the first goomba and hit the gold ring. Then jump on 4 goombas without touching the floor, then for every goomba you jump on untl you fall, or the gold ring wears off, you get a 1-up. My best record is 7 1-ups.