To attract patients who search on their own you want a lot of Google reviews. You have to somehow get people to go to your site and click the "Write a Review" button.
To attract referrals from other providers nothing beats repeated face-to-face interaction. If you get a chance to meet the other doctors in just about any setting they'll think of you when they need to send someone. If you seem personable, knowledgeable, professional, and not slimy or disgruntled they'll assume you're a capable provider.
I don't know if Facebook ads are very effective for a medical practice. They've been effective lately in getting me to buy a bunch of junk I don't really need though...