Punctuation doesn't have to be complicated. Use common sense as a guide. Sentences end with a period. Questions end with a question mark. Use exclamation points for exclamations and commands.
Commas tell readers when to pause.
They separate items in a list, or clauses in a sentence. If you are having trouble with punctuation, your sentence structure may be too complex. Start over and phrase what you want to say more simply. Be clear and brief. Say exactly what you mean.