I also suggest sharing meals and getting kids' meals. The portions are huge, so that's a great option for just about anyone who doesn't have a really big appetite.
Remember that any time a menu lists things as a combo (like a burger with fries), you can always buy individual items al a cart. The price may not be on the menu, but they'll do it. The combos really aren't designed to save you money anyway, so if you see the price for the combo and the price for just fries, subtract the price for the fries and you'll have a good idea of how much it will cost.