Of course, not everyone has networked their way around the industry so sometimes you have to start with the appropriate listing sites. The other way to do it is to find a recruiter you like, that you can trust, and that you don't mind talking to on a regular basis (it's sort of like finding a real estate agent - you'll be talking to this person quite a bit until you find what you want, so you need to make sure that you like them). I am not going to focus on the recruiters here, but I am going to help you find the places to go for the right kinds of listings.
If you want to find the appropriate listings, check any of these sites:
- Marketing Jobs
- Mediapost's Jobs Section
- iMedia Jobs
- Hot Jobs
- Craigslist (Bay Area for starters)
There are certainly other places to go, but these are as good as any to start!
Good luck getting the gig you want!