In the latest edition of his Podcast, Mr. Barrueco answers a lot of questions about his practicing.
He goes over essential technical exercises, using a mirror, memorization (really great stuff here), essential studies, and using a metronome.
The number one tip, I think: finding the hard parts, copying them, and putting them all in a folder. All the hard stuff is together for easy practicing. Very organized. Want to create a powerful technique routine? Combine the basics (arpeggios, scales/alternation, slurs, etc.) with the little, technical parts from pieces.
Thanks to Bobber for reminding me about these podcasts.