My company is looking to set up a preference center for email unsubscribes. I am unfamiliar with the process. Does anyone have any suggestions on where to start, what to include, etc.?
Check this post: Build an Email Preference or Email Subscription Center in Marketo in 10 Steps
This will help you to give a start at least.
Along with the post Ankit shared, I'd also start with importing the OP-Preference Center w. Double Opt-in v3 program from the Marketo program library. This gives you a good template of what fields to include, sample flows, and a sample landing page and email. If your company only markets to US leads, you can import the program that doesn't include double opt-in. While this template isn't perfect, it's a good start for you to personalize.
If you've never imported a program before, start in Marketing Activites and click "New", select "Import Program", choose "Marketo Program Library" and select one of the OP-Preference Center programs.
Hope that helps,