A few months working hard on your latest project made it possible to finish it a month before the deadline. Great! It might be a good idea to get some feedback before showing it to the client.
However, many of the people to whom you ask for feedback are going to limit their reactions to compliments. That's nice but you know your client is going to bitch about many details and getting feedback from people out of your area of expertise can help predict some of said complaints.
So what's a good approach to make other people comfortable to criticize even if they don't fully understand how it was done?