Building a team and putting one together can help you get through separation and divorce in the best and most constructive way possible. First step is to identify who you already have in the team.  Then identify any gaps. Use the existing team / word of mouth to help you find the missing elements.  

If you are going to work with a professional then make sure it is someone you feel comfortable with.  Have a preliminary call and see if this is someone you would like to work with.  The work itself is very difficult, it is even harder if you are working with a professional you don't like.  

Lastly make sure you maximise the benefit of working with a professional.  For example, if you are working with a counsellor to help with the grieving process, then let them know you will be mediating.  They will be able to give you tools to help you stay focused and regulate emotion in the mediation session. Make the most of the help you have.