There are a few ways you can prep tofu. You can cube it (or crumble it), marinate it, and be done. You can chop other veggies like sweet potatoes and red pepper and add your marinated tofu to a glass dish so it's ready to roast later in the week. Or you can bake or sauté tofu so it's ready to add to salads, soups, and whole grains.
For a super quick hack, buy Trader Joe's Organic Baked Tofu, cube that, and you're done in five minutes!