Jack, are you using just pattern 1 the E-shape?
Can I recommend you check out this topic Guitar Challenge (Improv) - Acoustic Pop in G Major (Justin Sandercoe backing track) where you will see and hear others making their first steps at major scale improvisation over Justin’s G major backing track.
See if this helps.
Just looking at pattern 1 of the G major scale. Here is a scale diagram with notes shown and the addition of three other scale notes in blue on the G, B and E strings (the strings you are most likely to bend).
Hope fully you can see that each highest note of pattern 1 provides an option to bend one whole step to another scale note.
On the 1st string you can bend from note A to note B. This would work especially well when you have a diatonic chord containing B (G major, B minor, E minor).
On the 2nd string you can bend from note E to note F#. This would work especially well when you have a diatonic chord containing F# (B minor, D major).
On the 3rd string you can bend from note C to note D. This would work especially well when you have a diatonic chord containing D (G major, B minor, D major).
DO not worry and get anxious about playing the changes. Just try those bends through a chord progression. When your ears make you smile at what they hear being good, the chances are you have played the changes well. If your ears complain and your smile fades, the chances are you have bend to a sour note. Knowledge is great. Listening is greater for the moment.
I hope that helps.
Cheers 
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