Rule: Set a vocative (nouns of direct address) apart with a pair of commas, if in the middle of a sentence, or a single comma, if at the beginning or the end of a sentence. A vocative of exclamatory force takes an exclamation-mark.
Examples:
Correct: I think, my friends, that we ought to vote for him.
Correct: Richard! Eat some ice cream!
Correct: Pattie, you make the best fried green tomatoes.
Practice putting punctuation (and/or capitalization) into these sentences:
Will you come with us David and Nancy?
Mark and Chris what was the name of the building where you got married?
Tuukka come away from that bear!
Resources for further explanation of how to punctuate vocatives:
The Comma Guide's Vocative Commas
Writing Explained What is the Vocative Comma
Grammarly's Commas