To coin a cliche 'it's not rocket science', you just have to be gentle and careful, and patient, the adhesive stuff is surprisingly strong and will NOT just pull apart, it has
to be cut, even trying to lift the glass to cut the bottom edge from inside the car, when you've freed the top and sides and you're thinking you've won, is risky and you've still gotta be gentle. I think it took me over an hour and probably nearer 2 to do, I wasted time trying to remove the dash but there must be fixings up behind the heater which I couldn't find so gave up with that, took off the bonnet, plastic shield and wiper motor, etc so I could get in with knife.
Think I've told you all I know; if you haven't already done so, go look at YouTube, there's several American guys who make it look very easy...
Oh and I read somewhere to leave a mm or so of old glue on the car and screen, the black 'paint' is some kind of primer which should not be removed (although you can buy it).