When you first appear, the steering wheel is straight ahead. To your left, you can talk to the Banktoad, who can keep some of your Star Bits for other save files. Behind the Banktoad, you can see the Mailtoad. He'll have a speech bubble over his head when he's got a letter for you. Under the place where you appeared, you can eventually switch between Mario and Luigi. Behind the steering wheel, you can grab a Cloud Flower. In the ship's right ear, you will find a Warp Pad that takes you to a Starshroom with a 1-up Mushroom on it; near this there is a Luma surrounded by Star Bits. In the ship's right ear, there is a pipe that sends you to a room with two Lumas: one gives you 1 box for 30 Star Bits and the other gives you five for 100 coins.
After Yoshi appears, jumping onto the ship's nose gets you to a Yoshi egg. Jump up the flowers to find a floating island with ten plants on. Eating them all gets you a 1-up.
After you complete the second star in Starshine Beach Galaxy, Climbing the Cloudy Tower (the one with no Yoshi) in World 4, behind the ship's hat, a cloud appears. Use Cloud Mario to get the 1-up Mushroom on top. There's a chimney in roughly the same area, which acts like a pipe and sends you to the inside of the ship, which displays trophies of the various power-ups you encounter in the galaxies. The exit leads to the brim of the ship's cap. This also works as an entrance. There's a Chance Cube on the ship's left cheek which gives you either a 1-up or a Star Bit.