I do give a small gift for every referral I give, but I usually only give say a $10 gift card, or a small gift.  

No different than if you were to get say a 10% increase in your insurance rates.

I don't fully understand the legal status during the waiting period, but if you can access the property to secure it you must have some rights.If so, perhaps you could offer it (say) as a studio space for artists.

Also how does a greeting card differ from say a postcard?

Some of my best clients actually run REIA's and even they say a large majority of the wholesalers are wandering aimlessly.

If, say, a five person group wants to rent from you, it could be mother, father, three kids; or mother, father, grandmother, uncle, one kid.

Of course, possum have a lower core body temperature = they almost never gets rabies and are not aggressive so let's just say a possum has nothing to worry about if it's caught by me :-)

I do my research and know the landlord tenant laws very well in all states and localities where I've owned rentals, which is why I know tenants in MD can sue landlords for 3X amount in discrepancy and that a landlord can't just say a security deposit is forfeit but must provide timely notification of itemized actual damages, plus they have much stricter lead rules, required rental inspections/inspection fees, etc... 

The one I like is to hear from the landlord prior to the current one.The current landlord might have incentive to say a tenant is fine, the one before that has no reason to hold back.

*I will add, it's noted as due payable upon delivery, it's not a pay-n-wait-n-see thing.But for, say, a $145k multi-scope "flip", there will be a detailed invoicing schedule of a deposit for commencement of job, typically 10%, with achievement markers for next invoicing.