It's the same as baking butter cookies, if you put the unbaked dough in the fridge for a few hours, they will keep shape much better. Basically the outer crust would set before inner crumb get a chance to melt and spread. It's especially important in the summer, when the mixed dough tend to be soft.

use shortening or lard. Butter has a lot of water in it and it will make your biscuits wetter when they bake than if you had used shortening or lard.

If you mix half shortening or lard with you butter it will make a big difference in the way they turn out. I'm not familiar with the recipe in the Bread Bible but when you make your biscuits you must knead them a little to develope a small amount of gluten or your biscuits won't hold their shape.