I'm going to jump straight to the point, so keep up (or ... read slowly). These are my go-to tips for being fluent in Google.
Tip #1: If you want information that's on a specific website, use "site: ...".
If I wanted to look for Prithvi Rakhyani on Facebook, I'd type Prithvi Rakhyani site:facebook.com. The first result will be my Facebook page (please don't add me). This is useful to me with broader topics, e.g. if I was looking for "iPhone 12 review" on "site:reddit.com" .
Tip #2: Find someone's Gmail account.
All you need is their name and "gmail.com", e.g. John Smith "@gmail.com". (Of course... if you're looking for a "John Smith", he's probably at home). P.S. this could potentially also work with other mail accounts.
Tip #3: Looking for promo codes for a product?
Simply copy and paste the following, and modify what you need:
site:twitter.com + "quip" + ("coupon" | "referral code" | "affiliate code" | "discount code" | "VIP")
In this case, I want to search for either "coupon" or "referral code" (or any of those terms) on Twitter, for Quip (an oral hygiene company). Feel free to replace either the website you want to search on, the product/company you want to search, or even the keywords.