Super Mario Galaxy 2 is a great game. However, it is sad that they give you just 3 lives. 3 Hits, your dead. Thats not Like Super Mario 64 nor Super Mario Sunshine, now is it? Nope. But it does redeem itself with the incredible amount of 1-ups that you get. Just on starship mario, you can get 4 alone, if your far enough. Now there are many places to 1-Up farm, but this is the easiest.
Make sure your far enough as to where you have the cloud mario power up on the ship.
Alright, now first, go to the StarShip Toad via teleporter. On this ship is a 1-Up. Now go to yoshi's egg, and do the flower/tounge things. Eat all the fruit that are on the hovering island. Thats another 1-Up. Now just drop down from that island, and there should be a dice. Roll is for a chance to get yet another 1-Up. No go get the cloud mario power up, and go to the back of the ship. Be sure not to touch the small river, or you will revert to normal mario. Now go to the back of marios hair. The screen should pivot up revealing a high cloud, with a 1-Up on it. Now just make clouds and get on up there. Thats 3-4 free 1-Ups. Now just drive the ship, and go back on. They've all reset. Now youll never get a game over.