I haven't made an apple pie for ages, but do a lot of tarts, and have learned how to avoid the dread soggy bottom.
I always make my own pastry, but I don't have anything against shop bought for an easier life. My sweet short crust pastry recipe is 200g plain flour, 1 tablespoon icing sugar, 100g cubed butter. Rub together til it resembles breadcrumbs and use 1 beaten egg to bind together. Wrap in cling film in a disc shape in the fridge for at least 30 mins.
Roll out on floured cling film, which makes it easier to pick up and line your tin.
Grease your tin and then sprinkle flour on it - makes it so much easier for the tart to come out.
Once you've lined your tin, push right into the corners, and leave the excess hanging over the sides at the top of tin (remove once fully cooked)
Prick the base of the pastry all over, put grease proof and baking beans on to blind bake, put on preheated baking tray at 180c for 10 mins. Remove beans and paper and bake for another 5 mins (if the pastry still looks a bit wet give it another couple of mins)
You should now be able to put whatever filling you want it and bake accordingly.