id stick to snails and shrimp... 5 gallons is pretty small... the smaller the tank the harder it is to keep yer water parameters where they should be.. and being new at fishkeeping is not going to make it any easyer..
so my vote is to stick to the simple stuff.. or to get a 10gallon which is still small but much easyer to maintain.. then go with the classic "first fish" guppys and platys (easy to care for.. they breed like crazy (live bearers) and they are pretty hearty so messing up the parameters wont kill them instantly.. id stay away from dwarf puffers just because you cant really keep anything else with them (they are fin nippers)
get the biggest tank you can afford
dont try to save money now because you are going to lose it all like me buying a fish tank thats a little bigger, and then another one thats a little bigger;etc because you get so addicted