Great topic gentlemen! If one were to play a 'hammer-on from nowhere' then that constitutes as 'one note.' Another approach is to play the 'one' note (in this case 'C') over different chords and listen to how it affects the chords: Over a 'C' chord 'C' is the root and sounds obvious. Over an 'Am' chord 'C' is the minor 3rd and has a different harmonic feel. Over an 'F' chord 'C' is the 5th doesn't sound as colorful as the 'b3rd' over 'Am'.

Here's where it gets interseting: try playing 'C' over 'Dbmaj7'. It's the 'major 7th' and is jazzy sounding. How about playing 'C' over a 'Bb major or Bb minor chord', which produces a '9th' sound, or 'C' over to get a 'Ebmajo7' '6th' sound.

Also try experimenting with vibrato and sliding into the note from above or below.

I hope this helps!

-Dave