2. Never Avoid A Coincidence... Unless You're Busy
The Doctor and, it is assumed, the Time Lords in general are highly in tune with coincidences in space and time. Typically, our hero will explore these coincidences immediately, but there are times where he's simply "busy" and chooses to seemingly forget about it. This happens to be an aspect of his charm, the Eleventh Doctor more than the others, to pull up the memory of these coincidences later on in order to save the day. Lesson Learned: If you notice a coincidence, keep it in mind as it might have been something deliberate instead.