For the first frog encounter, I have heard that African Dwarf Frogs, Oriental Firebellied Toads, and White’s Tree Frogs are excellent starter frogs.

In my opinion, I believe that the White’s Tree frog is an excellent frog for beginners and experts alike. I own a Whites Tree Frog and he is so cute, has a fun personality, and is really easy to care for. However, it has been said that most young kids bore of them quickly as they are nocturnal creatures and are most active at night.

You can also check out the article that Raya recommended. Also, here is the link to an article I referenced when I first was trying to decide on what frog to get .
Your First Frog