You actually need a larger tank if you want to master the basics of the "Waterkeeping" hobby. I started seriously in the hobby with a 30 gallon tank. There needs to be a lot of water in a tank to allow for mistakes in what is called "tank management". Everyone makes them, but if you have a larger tank, then your fish aren't as likely to be hurt because of poor water conditions.
If you want to guarantee success in this hobby, you should go with a larger tank. You'll feel better, because your fish will survive your "learning curve".
Just a thought or two.
"Aquarium (Water Building) Keeper"