What is This Thing Called Love?  - Arpeggios 

Knowing the arpeggios of the chords ensures that you can play inside the chord structures.  This will help you to improvise around the changes.  It is not the sole answer to good improvisation but it will help you to construct information about what the chord tones are.  I've played the arpeggios up to the 9th and played the b9th on dominant chords.  Remember that this tune is an AABA structure so after you have played and sung the B section, you still have one more A-section to go to complete the form.  

A Section - Arpeggios