If they've not experienced something similar to the mental health problems I'm suffering from it's usually best if they treat me as normal. The effort required to try and explain aspects of what I'm going through, usually with little success, is often far more detrimental than any benefit they could hope to provide. Being distracted from the problems, even if only for a short while, can be blissful and hugely appreciated.
On the other hand, I'm usually happy to be treated differently by people that have had similar experiences to me. I can often communicate to them in a sentence things which would take hours of conversation with somebody who'd not been there before.
It's a difficult situation for both the supporter and the supported, particularly in the early days.