Try shopping only the perimeter of the grocery store – the produce section, bulk foods section, fresh meat and seafood counter and dairy sections – since the middle of the store is where all of the packaged, processed stuff lives.
Try to replace one processed food item that you usually shop for with a whole food version. Like boxed rice with seasoning packets? Try making your own. Same goes for soup. Grab the same ingredients from your favorite canned soup and try to make it yourself.