Twinmotion & Vectorworks classes

Hi, I have used Twinmotion with VW a few times and in summary cannot get a grip on how to manage thing wrt objects and applying materials.

When I apply a material in TM, (not always) the material is applied to, what seems are unrelated objects.

I think I am struggling to get a grip on how things are imported across (I use datalink).

Ideally I would like each object to be able to to have a material applied on its own.

FYI, I am a landscape architect so am dealing with things like walls, ground surface treatments, etc.

What are the best practice rules when setting things up in VW and TW?

Thanks