How are you?

Ciamar a tha sibh?

To ask a person how they are in Gaelic, you use:

Ciamar a tha sibh?
How are you?
Ciamar a tha thu?
How are you?

Two general ways of answering the question “Ciamar a tha sibh / thu” are:

Tha gu math
Well
Chan eil gu dona
Not bad