Well what are you interested in? There are lots of species that are easy(ish) to breed, and the amount of fry care is very dependent on what you choose.
Easy/almost no fry care species might include
Live bearers (There are plenty of wild strain live bearers out there, if the common guppies/platys/mollies/swords don't interest you)
Many species of cichlids- my personal favorite for new-to-cichlids keepers is the common kribensis- Pelvichromis Pulcher. 30 breeder is a great size for them- keep them in sand or very small gravel, so the pair can clean their cave, and they pretty much take care of the rest. Just feed the babies and stand back!
More fry care species (ie get the eggs out of the tank and care for them yourself, or at least in a breeder box)
Some species of corydoras, rainbowfish, killifish, angel fish (probably too big for a 30 breeder tho), white clouds, and anabantoids (gouramis and bettas). Make sure to buy tank raised if at all possible, as these are almost always far easier to breed, and more forgiving of water parameters.