Use a colon principally at the end of a fragment that introduces a list.
A colon can also be used to introduce dialogue or to separate the main title from a subtitle when cited in running text.
Occasionally, a colon can be used within a sentence to indicate that what follows the colon illuminates or expands on what precedes the colon.
Do
The words were: dog, pencil, hypotenuse.
His favorite show was Star Trek: The Next Generation.