If you can find it, get a low protein flour like pastry flour (Swann's cake flour) or White Lily.
The lower protein from the soft wheat makes a BIG difference when you're trying to avoid making gluten, which will make the crust tough.
If you have to go all purpose flour, go with the vodka (gin is also good) substitution that was recommended, as that cuts down on the water available for making gluten.
Cut your fat into the flour well. By coating some of the flour grains in fat, that helps keep them from absorbing water, which also cuts down on gluten formation.
And for god's sake, don't do what a friend did a few years ago and use bread flour because that's all he had. Those crusts were absolutely bullet proof.