Watch the Adding Fills & Runs online guitar lesson by Fareed Haque from Solo Guitar Handbook
Tempo rubato ([ˈtɛmpo ruˈbaːto]; "free in the presentation", Italian for "stolen time") is a musical term referring to expressive and rhythmic freedom by a slight speeding up and then slowing down of the tempo of a piece at the discretion of the soloist or the conductor.
The best place to steal time is between phrases. Again, common sense needs to prevail here. Sing or say "A-ma-zing Grace", Would you break in between "A" and "Ma", or between "Ma" and "Zing"? Nope, most of us would say "Amazing Grace", take a breath, and then proceed to "How sweet the sound." Follow the phrasing of the words, follow your own breathing, and then you'll find the natural spots to breathe, steal some time, and add in something flashy and tasteless. Ha!