Twelve power binocs are very helpful, specially when the eyes are more than 60.
You'll spot squirrels you never saw before.
Listen to their chittering. When it's loudest, they're looking your way, and you stay still. When it's fainter, they're looking away, and is your time to maneuver to see them better.
I used to use shooting sticks. Still are handy. But try out different positions, like resting the rifle on your leg, the fleshy part, when sitting back in a semi-reclining ground based position.