I've just started learning Mandarin and I was curious as to when it is appropriate to answer a yes/no question negatively with 沒有. Obviously, if the question involves 有 then it makes sense. However, I understand that
你在做飯嗎?
could also be answered that way as well.
I also understand that questions about being, such as
你是老師嗎?
should be answered instead with 不是。
Is this a general rule? That is, unless the question is about being or state, is it safe to assume that I can respond with 沒有?