(a) Use a comma in a sentence pertinently but don’t overuse.
(ex) Prefer I love you too rather than I love you, too.
(b) Use commas to count numbers or to list several items.
(ex) 1, 2, 3
(c) If commas used for movie titles, lyrics, etc. in transcription, it may use in the same position in subtitles.
(d) Do not mark a comma at the end of a sentence.
(ex) I heard that it’s right, (X) I heard that it’s right. (O)