Yes! - when you are strongly in favour <including or> want your opinion to carry a lot of weight
Yes. - when you are in favour, xor when you are strongly in favour personally but don't think it must essentially be the right choice for everyone and would also be okay with another choice winning if that is more popular
Neutral - when you aren't sure whether a solution is good or bad, you think it's irrelevant to you, you don't care
No. - when you are against the proposition, xor when you are strongly against it personally but don't think it must essentially be the wrong choice for everyone and would also be okay with this choice winning if it is more popular
No! - when you are strongly against the proposition <including or> want your opinion to carry a lot of weight