So nice to have you come to the community!
There is a great link in my signature about keeping fish, even for an old hand at fish keeping there is a bunch of info which could prove useful. It helped me.
My suggestions would be to think about and start looking at fish appropriately sized/and kept in a 30G.
Some helpful resources are liveaquaria dot com and aqadvisor dot com, they can help tell about fish, also aqadvisor will let you log your tank size and filter size and you can see how many of which fish you like can be in the tank. Mostly a loose guide, we can help you more in the "FW
- getting started" section when you decide to post a thread for your tank.
Freshwater & Brackish - Getting Started - Aquarium Advice - Aquarium Forum Community