If you want to know how to play blues sax you’re going to need to know three basic chords- the I, IV, and V.
The basic form of blues goes like-
I7 | I7 | I7 | I7
IV7 | IV7 | I7 | I7
V7 | IV7 | I7 | I7
So it starts on the one chord, goes to the four chord, back to the one chord, to the five, to the four, to the one.
There’s something called the ‘blues scale’ that works pretty well over the blues, BUT you don’t want to play it exclusively. It gives a certain sound, which is cool part of the time, however you want to shake things up and throw other things in there.
The blues scale in G goes like:
G – Bb – C – C# – D – F – G
So the root, flat three, four, sharp four (aka lowered five), five, dominant seventh.
One of the good things about knowing the blues scale is that once you have it under your fingers, you can just play the saxophone and not worry too much about notes.
Use it part of the time, but not all the time.
Learn how the chord changes relate to each other and what notes give them distinct sounds as you progress past using just the blues scale.