Sentence after a Colon
The first word of sentence following a colon is capitalized.
Correct: Grapes were not squeezed for juice: The pulp was pressed.
(A complete sentence follows the colon.)
Incorrect: Please bring the following items to work tomorrow: A grab-bag gift, a goofy hat, and a smile.
(A list follows the colon, not a sentence. No capital is needed.)
The first word in each line of most poetry is capitalized.
The Words I and O
The single-letter words I and O are always capitalized.
Note: The word O is used in direct addresses (as in "O Tannenbaum" or "O Pioneers!") The word oh is an interjection expression surprise (as in "Oh, look, Jane!")