Watch the Rubato Playing online guitar lesson by Mimi Fox from Flying Solo
Where there is great freedom, there is great responsibility! Rubato playing is a challenge for solo guitarists because many students are unsure where to start/stop a phrase. The trick is to use rubato playing as often as you can to see how it feels to you, and always tape your playing. Sometimes I will play a very long passage of single lines. Other times I might use some staccato bursts of chords that set up or end a song. It's all about creating a mood. Listen to other guitarists/pianists/horn players/vocalists using rubato ideas. This should spur you on.