Also due your due diligence on whatever is specific to your location: radon, expanding soils, next to the goodwill (dumping)... whatever you need to watch out for in your area, do your own due diligence. 

Hello Everyone,I am considering leaving a gift or a couple items for new tenants upon move-in as a gesture of appreciation and goodwill.

There's a lot to be said for creating goodwill with tenants, especially in the beginning.  

Here are two examples where knowledgeable and experienced friends made mistakes:A well established park owner bought a park and paid for it without separating the good will and equiptment from the actual land in the purchase because the contract was vague in that area.

I know of FREE on craigslist and Goodwill.  

I don't think a birthday card will gain any good will. 

I plan to take care of it as an act of goodwill since the tenant has been very good and self-sufficient, but I don't know if it's actually a problem that I'm responsible for.

I would be inclined to give some goodwill and let this time slide, but not again, and if it happens again soon, consider looking for another tenant.  

Sounds good - will wait for your verification..

Then, I guess I would try to talk to tenants and find out any pains they may have and then upon solving these problems and gaining some good will, get in and get new leases signed with some upward rent movement.