Techniques for teaching reflection and critical analysis to unprepared students
Almost certainly this is going to be a multi-stage, complicated process, with no simple answer. However, here's something relatively simple to start with, maybe. 

I'd suggest starting with collaborative peer-evaluation. Create an assignment which has a peer-evaluation stage (with no reflection on the final grade). The peer-evaluation stage consists of sitting them down and working through each person's output as a group. Ideally, you'll act mostly as guard-rails for the discussion, keeping it on-topic and professional, while providing some initial thoughts. 

The goal of the peer-discussion phase is to start getting them to think critically about the output, from both the perspective of a creator and a consumer.

After the discussion stage, then allow them to take the feedback and re-edit their work to improve it, grading only the final result.