The key to crusty bread is quite simple: lots of steam. Steam allows bread to expand to its maximum limit, decreasing the chances of a flat or tough crust. Introducing steam into a home oven is easy and produces great results.
Preheat oven to temperature specified by bread recipe.
Place empty baking tray on the bottom rack of the oven as it preheats.
Prepare your bread recipe as usual.
Fill a measuring cup full of cold water when you are about to put the bread in the oven.
Place bread in the oven, then immediately pour the cold water into the baking dish.
Close the oven door, let bread bake, and voilà! Your crust should come out crispier than ever.
If you don't have a baking dish, you can try spraying some water into the oven instead.
Pouring the water into the baking dish will create quite a bit of steam, so exercise caution.