Scales to Play Over E7b9
Every chord is a subset of several scales: any scale that contains all of a chord's tones fits over it. Pick a chord to see the matching scales from its own root, the major keys the chord belongs to, and full fretboard diagrams for every scale on guitar.
An E7b9 chord contains the notes E – F – G# – B – D. Any scale that includes every one of those 5 tones fits over it — from the root E, that means E Half Whole Diminished and E Spanish. They differ only in the notes between the chord tones, and that is where each scale gets its color.
E7b9 is not diatonic to any major key — it is a chromatic color chord, so treat it as a moment of tension: lean on its chord tones from the scales above, then resolve to the surrounding key when the progression moves on.