This is a really nice thread. I don't think I've seen one like this here.

These are a nice compilation of suggestions. Here are mine:

• make sure the therapist you are seeing has done their own depth therapy
  
• tell them about your issues at the 1st or 2nd session to make sure they are safe enough to do therapy with (don't spill out everything, just tell them in a general sense f you have attachment issues, sui thoughts, hospitalizations, anger problems, addiction, etc)
  
• start therapy at as young of an age as possible

Surprised at some of these posts. It never occurred to me that being honest or trying to be open had to be explicitly stated. I just assumed it was something people did or set out to do due to the nature of seeking therapy.