I don't like writing validations, it feels like busy work. So if I do
them first, I drag my feet on the start of a project, if I do them last
I drag my feet at the end.
I think the proper way is to do them first. That way you have a solid
model to play with in your controllers and views, and you don't have to
worry about the funny errors about nils here and there. It'll force
you to do things correctly.