I would do both.
That is what we do.
But, also list your business.
We get calls from homeowners and realtors to provide services.
Where to be listed.... you need to understand that I do marketing full-time.
I work with my brother-in-law, helping him. I handle the operations side.
So, you are really asking how to do SEO
. Since you want to be found for mold remediation.
You need to be listed in Google + Local, Yahoo, and Bing
At least 100 citation sites. Sites like Merchant Circle and YP.com
Relevant business directory sites.
As well as submitting content to content sharing sites.
Articles, videos, pdfs, audios, ppts, etc.
Hope that helps.