Least and most difficult of the 7.5 steps...

Easiest: Play. The easiest way to learn to do something is to do it for fun. It helps if the thing in question happens to be fun to do.

Hardest: Deciding which habit is the hardest for me. Oh, I dunno; maybe "Beginning with the end in mind". I will often start something having only the vaguest of ideas of what the end result should be. Sometimes, I end up wasting my time. Other times, serendipity strikes and I end up with something pretty cool.