The two most commonly used buttons are the Sleep/Wake button and the Home button. Since you'll be using the Home button often, take the time to define what screen should appear when you tap the Home button twice in rapid succession.

If you like curling up in a chair or sofa with your iPad, you may find the Screen rotation lock switch especially useful to keep an image fixed on the screen no matter which way you rotate the iPad. Without this switch, you could tilt the iPad slightly and suddenly see the image flip back and forth as your iPad tries to figure out what orientation to display its screen.

Finally, don't forget that the Volume Up/Down buttons can help you crank up your music or lower it so you don't disturb others. By acquainting yourself to the purpose of these physical buttons, you can quickly control your iPad. Once you know how to control your iPad with the physical buttons, the next step is to start learning how to control it using touch gestures on the screen.