I cannot sugar coat the importance of commas! Below are some simple rules to get you started on the fast track to conquering the dreaded comma!
1. Use commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.
2. Use commas after introductory a) clauses, b) phrases, or c) words that come before the main clause.
3. Use a pair of commas in the middle of a sentence to set off clauses, phrases, and words that are not essential to the meaning of the sentence. Use one comma before to indicate the beginning of the pause and one at the end to indicate the end of the pause.