Advice from the coalface
One of the most pivotal but also most difficult jobs in the creation of a web site is the project management. I think it's difficult because the project manager has to be good with people (“client facing”), have an overview of what is technically feasible, desirable &/or achievable, and also have a design sensibility that doesn’t offend. They also have to be diplomatic, well-organised, clear-minded and foreceful when required.
From a web builder's perspective, the most important thing is to know what needs to be done and when. Doing the work is straightforward. It can be fun, challening and sometimes dull. But it's straightforward. Not knowing what the actual work is or what the deadlines are is really undermining, as it can become a constant background worry which actually detracts from your work.
So, here's how I see the process:
1. Client: What needs to be delivered and when.
2. Plan: What work needs to be done and for how long.
3. Schedule: Who does what and when.