This is the perfect trick for beginners.
Show 2 black containers with red lids and a die. Have a spectator choose any number on the die. They place their chosen number face up inside of the container and the lid is placed on it. This way there is no way the magician can see which number has been chosen. The magician then places it in a second box and puts the lid on. This guarantees the die is fully concealed within. Even though the die is contained within the boxes you will always know which number it is.
The trick can be repeated. It’s very easy to perform. It takes only a few minutes to learn. It takes up very little pocket space. Any number can be chosen randomly each time. Looks like you’re reading the mind of the audience.