George Gershwin - Rhapsody in Blue
There are many stories surrounding the insertion of a portamento at the beginning of this piece. I'm not certain which is true, but it is certain that one must do it! One should also put in portamenti, bends, vibrato, and other Jazz-era effects throughout this solo. The original recording is available on the US Library of Congress website. I urge you to listen to it there, and from many other sources. There are many, many ways to make this solo interesting, and the grungy, grimy, slinky, back-alley thing it's supposed to be. Remember: Jazz was the new, the underground, and this was an age of prohibition where Jazz was often a signal for the forbidden. It is also early Jazz, so if notes are swung at all, it's barely so.
Enter p, and don't give things away too quickly. Start your scale slowly, but quickly get faster. After you cross the break, go from glissando (notes) to portamento (slide) gradually. Make a half-portamento in between by using only your lips for the slide, and pick your fingers up normally. This makes it sound more natural than if the portamento starts suddenly. I like to slide down to the grace-notes in the second measure, again to the third measure G, and yet again to the G at the end of that bar. I like to do a long, slow, deep bend on the long open G, resolving to normal vibrato, and imitate this with larger bends (as they become more possible) on the following two whole-notes. The first bar with trills is the nadir of the phrase, and should be p. play each step up more loudly, ending with the bar before 1 at f. Bend the high F, then stay on it fermata. Slide down to the D, then slide up the high C and then immediately down to the F at 1 without lingering on the C. It should sound as if you've done one big bend up and down, that just happened to peak on the high C pitch-wise. Put another portamento on the scale before 2.