A good counselor is like a good shadchun and a good shidduch. You have to keep trying till you find the right one. A good counselor is going to side with the Marriage and not with one spouse or another. If a counselor sides one way or another it is time to find another counselor! No counselor should be biased in either direction and should always be working to save the marriage! If either spouse is uncomfortable the counselor should refer them to someone else. That is a sign of a good counselor because saving the Marriage is the goal not giving points to either side for being right. So the basics would be what can either side do to make the marriage work and what are both sides willing to do to make changes in the Marriage to make it work.
And BTW that goes to any RAV you go to as well. Both sides should be equally right and equally wrong. The mediator should be able to see each issue from all perspectives.