How to make a lattice pie crust?
There are two keys to this. First, work right on the pie and start in the middle. Second, fold strips back to make it easy to do the over/under.



This picture, from  http://localfoods.about.com/od/preparationtips/ss/latticepiecrust_8.htm, is kind of the aha! moment for me. Fold half of the vertical strips back, lay a horizontal strip, unfold the folded strips and fold the ones that weren't, repeat.

Trim extra length from the strips, and use eggwash to glue them to the bottom part of the pie, where it comes up at the edges.

You'll have extra dough what with the trimmings and all - just use it to make a freeform gallete or the like. If you have no extra pie filling, use jam, or butter/brown sugar/raisins. Way less trouble than trying to make exactly the right amount of dough for the lattice.