That is exactly what NOT to do. Attorney has many years of time in on how to approach mediation, and mediation is not the place to make catastrophic errors. Overly emotional parents tend to fare worse than logical parents as a general rule. Parents that are dead set on certain conditions, times and places, and not being flexible, often do not help. Each case is judged on the merits and pitfalls of everything involved (assuming we know what is really involved...)
It is true that some parents come to the table with facts that are not exactly great, but some parents may lie in order to get what they feel is fair. Mediators have heard many stories over the years and hopefully the mediator you get won't be one that rushes to judgment.
If you have never been to mediation or have already lost in mediation, and wish to change your status or change the parenting you have, you may have to do some work. The SHARP office may be able to help you with paperwork; if you need legal advice, you should consult an attorney to make sure what you are doing is correct.