it's not incredibly difficult to come up with a successful premium for a breakfast cereal. just think of a good prize to put in the box. usually a cheap plastic toy. when the dark knight was in theatres, they put little toy batmans and jokers in cereal boxes. a couple different versions of each. i must've bought five tons of reese's puffs in my quest to collect them all. and i'm an adult.
the worst kind of premium you can do for a cereal is one you have to send away for. i can't tell you how many times in my life i opened a box of cereal and inside, there was only cereal. if it's too impractical to literally include the premium in the box of your cereal, there's only one solution-- change your premium. i don't care if it's the worst piece of shit in the world; when i open a cereal box, i expect to get a prize.
small toys or devices made of plastic are ideal. a tiny action figure is maybe the best. the most disappointing in-box prize i would say is flat stuff, like any sort of trading card or paper cutout, because you can always just include those on the back of the box. when i was little, cracker jacks used to come with tiny replicas of vintage baseball cards. i thought those were terrible then, but they were gold compared to the paper pictures that come in cracker jacks today. you're supposed to like cut it out and do an activity with it. i don't know any kid in the world who would see that and not immediately recognize it as garbage.
but you can also give a prize that creatively ties into cereal time. the best spoon i ever had came in a box of cap'n crunch. it was a red plastic spoon with the head of a tyrannosaurus rex. like, the spoon itself was the lower jaw of the rex head and on top was the upper jaw, which you could open and close on a hinge with your thumb. you could eat anything with this spoon (not just cereal), and it made everything better, because before every bite, the process of shoveling food onto the spoon made it look like the dinosaur was eating your food (and then you could eat it). pudding was especially fun, because then it looked like the dinosaur had pudding all over his face.
for a while, teenage mutant ninja turtles cereal came with teenage mutant ninja turtles bowls. and not tiny bowls either. regular-sized bowls. how did they fit regular-sized bowls into the box? they didn't. they strapped those fuckers to the front of the box with shrinkwrap. and when i say they were teenage mutant ninja turtles bowls, i don't mean they were bowls with turtles painted on them. each bowl actually WAS a different ninja turtle, with a head and appendages coming out of the side.
you could collect all four turtle bowls, and you didn't have to buy a million boxes to do it, because you could see the bowls outside the box, so you knew what you were getting every time. i can imagine some people not seeing the point in collecting all four, since they were seemingly identical in all but eye mask color. but each teenage mutant ninja turtle bowl was as unique and beautiful as a cosmic miracle. eating from a leonardo bowl was absolutely nothing like eating from a michelangelo, donatello, or raphael bowl. and if you knew one fucking thing about life or art, you knew that.
once you've opened a box of cereal and claimed your prize, you still have to finish all the cereal in the box. many days follow when you're just eating that cereal without any additional prizes. at the end of your life, those are the days you won't remember. just try to eat a lot of cereal whenever you can, so you can finish it and finally get a new box of something. and pray. that what will have been your favorite prize is in a box somewhere that remains to be opened.