Hello SITM!

I am brand new to making music. I wrote a song, lyrics, melody and chord progression. I have a few friends who have joined in the project to help me come up with other instrumental elements and percussion. One of those friends will help me mix and produce the song as well. They have not asked for any compensation at this point (its very much a for-fun project), but I want to make sure I keep it in mind to make things fair incase we do ever release the song. What is a typical payment arrangement for such a set up?

Thanks so much! I am so excited to join this community!