I just started using SPD type "clippless" pedals and shoes.

Last Sunday I was taking an alternate route and hit a big hill, I shifted down and started to spin my way up it. I got about 3/4 up and started to struggle and wanted to unclip in case I stalled so I would not fall down. I had a hell of a time doing so because I was in a real low granny gear and spinning furiously. I just couldn't manage to swing at least one foot out while maintaining a cadence that was enough to keep me stalling out.

So does anyone have a plan of attack to use in a similar situation? Unclip BEFORE the hill? That would remove the advantage the SPDs have of being able to PULL up on the pedal on a hill.

AND, what's the best way to push on the pedals without accidentally clipping back in? I try to hold center my shoe over the pedal but then it slips around and I've accidentally clipped back in a few times.