1. Wrong: We brought everything we needed for the trip a camera, a phone charger, and good attitude.
Better: We brought everything we needed for the trip: a camera, a phone charger, and a good attitude.
Explanation: The colon after trip makes clear that the following list is everything needed.
2. Correct: Over the summer, I read Prep, The Catcher in the Rye, and Into the Wild.
Explanation: Since the list follows the verb read, no colon is needed. This sentence has a compound direct object, punctuated correctly.
3. Wrong: After reading the report, I have one question, how can the company stay afloat?
Better: After reading the report, I have one question: How can the company stay afloat?
Explanation: The colon clarifies that what follows is the one question.