Whatever you do when you hire a web designer, document everything from Requirements to Deliverables to Schedule to Responsibilities to Price to Payment Schedule. The more detailed, the better. Leave nothing to chance.
Consider this to be a unique project and not a process (that comes later after the project is done).
Learn about web hosting company, cPanels, and all that (do backups regularly).
Learn what you need to because you need to be versed on all this stuff unless you have boatloads of money.
Initially, I tried to support local people and they gave enough headaches that I found a good one one time zone over, everything done remotely.