This tip may sound counterintuitive, but you should write Foundations of Canadian Law last. Foundations is by far the trickiest exam to prepare for because the exam questions are unpredictable. Make sure you know each of the topics inside out, but more importantly is to make sure that you have read all of the required articles. When you're faced with an essay question on the exam where you cannot recognize what topic you're being tested on, try and think about the articles you have read. Many times these questions are hinting to deeper discussion of the articles. Also know that you may have to refer to several topics on the Foundations syllabus when forumulating an answer to a single question on the exam.
Because of the unpredictability of the exam, I recommend that you write it either after you have written admin and consti or at the same time as those other two courses.