Formal:
* Helo, ffrind dy gariad: This literally means "Hello, friend of your love" and is a more polite way to address someone.
* Helo, ffrind: This means "Hello, friend."
Informal:
* Hei, ffrind: This is a more casual way to say "Hello, friend."
* Hwyl fawr, ffrind: This means "Goodbye, friend" and is a common way to end a conversation.
You could also use a specific name instead of "ffrind" (friend) for a more personal greeting.