Best to just stay with the vehicle especially if you do not know where you are and do not where you are heading if you want to walk out.

http://www.youtube.com/watch?v=0CT0470DVKE

http://www.youtube.com/watch?v=DJkG4H4x8pE

http://www.youtube.com/watch?v=tORer5pJJxM

http://www.youtube.com/watch?v=g3XhZOyisrU

Although in this tragic case just because this unfortunate woman had a GPS it didn't mean she knew where she was, let alone know in which directional to head off to, even if she attempted a hike out. She also had a working vehicle, which was capable of being driven out if she had the ability to get it out of the hole it was in. A lot of folks just give up if their vehicles get bogged down when a little more persistence will usually get the vehicle free, even if it means digging it out all night long (assuming of course she even had a shovel).

Even leaving the tyre behind was a mistake as it would of made a nice smoky black signal fire. She should of made herself a cup of tea after changing the tyre and had a little think about what she was going to do next and to calm down. It sounds as though she panicked when she got the first puncture even perhaps thinking travelling off road over sandy terrain would have made the chances of getting a second tire puncture less probable.