As with any business, ask for client referrals.  

I'm looking for any referrals for a structural engineer, the property is in Elmhurst, IL. 

What I am wondering about is whether or not I should get my real estate license so I could earn referral money?

*Some investors pay a consultation fee or a referral fee to bird dogs which are shown as a line item on the settlement statement.

Contact commercial real estate brokers who deal daily in the product type and they will definitely have lender referrals.  

@Jason Turo I have used pretty much any lock out there and must say Lockstate currently beats all products on the market and is the first smart wifi lock or product for that matter, that got officially promoted and supported by Airbnb, VRBO and the channel management solutions such as Beds24.I use Lockstate in all our rentals in Germany, Tuscany, and the USA.

If you advertise corporate housing and get requests but cannot help them because your property is rented, we pay BP members referral fees.

(If I know how to calculate one of the promotional offers, I can figure out how to calculate the others.) 

Do your research, get referrals, and find people walking the walk.

They tell you if you bring in a client to purchase you will get a referral fee not a commission because you are not a member of blah blah association. $ is split with their league members.