Foolproof Pie Crust

I use to make pies for my grandpa, one of the last things I made him was an apple pie with his Granny Smith apples he grew in his yard. But at the time I had yet to perfect the perfect pie crust, so I had to go with store bought. He was such a gem, always proud of his grandkids so even if it tasted absolutely terrible or was "semi-homemade" he was always impressed. I vowed to perfect a homemade pie crust ever since and now, I can't even imagine buying crusts anymore.