| Play the scales you already know. But try and figure out fingers that use all the strings up and down. Try switching up fingers on the way up and down. Try playing the scales up and down in sequences (especially odd numbers) like C D E F G, D E F G A (in 5/8 or 5/4...5/something). Do that up and down. Try playing the scales in 3rds, 4ths, 5ths, 6ths, 7ths, octaves, 9ths, etc... Like thirds would be C E, D F, E G... Go up and down with those. Try alternating "up and down" for examples 7ths would be, C B, C(octave higher) D, E D. E(higher) F...Arpeggios across all the strings help with string crossings alot. Anything arpeggio will work. I also like running Whole tone and Diminished scales up and down, one note higher each time. Whole tone for example, C D C D E D C D E F E D C D E F G F E D C etc until i get to the top of the neck, then I take one note away each time.
Good Luck | 
