If they have some charge, that can be really attractive
If they can hydrogen bond, that can be pretty attractive
Otherwise I end up guesstimating electronegativity and try to imagine which atom ends up with all the electron density for some polarity. Then I try to think about how these polar molecules could attract each other.
So, like, with O=C=O you would think that there isn't really any polarity, but with O=C=S there would have to be because oxygen is so electronegative in comparison to those other two atoms. So I'm pretty sure O=C=S would have more intermolecular attraction
I'm usually wrong, but I think this is correct