Do not use a separating comma after the coordinate conjunctions -- and, but, or, nor -- nor after the one-syllable conjunctive adverbs -- thus, hence, still, then, so, yet. However, don't forget that a pair of commas can go anywhere.
...And he was not involved in the issue with the report.
...And, Ms. Andrews, he was not involved in the issue with the report.
...But I haven't seen him in months.
...But, Counsel, I haven't seen him in months.
...So when did you first realize there was a problem?
...So, in other words, when did you first realize there was a problem?
Happy punctuating!
Margie