I am getting ready to start building a new web project in my spare time to bring to fruition an idea that has been bouncing around my head for a while.

I have never gotten down whether I am better off first building the model and then the consuming application or the other way around.

What are the best practices? What would you build first and why?

I imagine that in general the application should generally drive the model, however the application like many websites really doesn't do much without the model.

For some reason I find it easier at times to think in terms of the model since the application is really just actions on the model. Is this a poor way of thinking about things?

What advantages/disadvantages does each option have?