Art Modeling, a two-part question: How to ask a potential model, How would a model prefer to be asked? (This is outside of a classroom setting)

I’d like to know, as an Artist- how have you approached a potential model (for portraiture or figure studies, any medium)

As an Art Model (or potential one) how have you been approached, or would prefer to be asked?

also, What were your terms, and was there a model-release form involved? (recommended)