Having finished the Esperanto tree, I am now octolingual: my native English + seven other languages! (Well, not really, but at least I have a Duolingo smattering of the other seven.) So far, Esperanto is the easiest; No surpise there. If only I could find someone to speak it to.
Aquí (acá) se entiende si dices (decís):
Here it's understood if you say:
Felicidades (this one is used for semiformal birthday greetings here)
Enhorabuena (although I've heard this, I think, only once, here xD)
Congratulaciones (as a joke, no one uses this word for real congratulations)
And maybe some others ;)
You can certainly find esperanto speakers online!
Or the lernu instant messenger is great for text chat.