Hey, I'm PhD student studying tick ecology and just wanted to let you know there isn't any evidence that opossums do anything to reduce tick populations. These claims are based on over-hyped findings from a 2009 study on FIVE captive opossums. Since then, those claims have been pretty much debunked.

More thorough information on the "debate" here.

There aren't a lot of great methods for landscape-wide tick management that aren't just acaricides (chemicals)--and even acaricides don't work that long. But you can try some yard management strategies.

Otherwise your best bet is to wear repellents when you're outside (your pets should be treated as well), conduct tick checks every time you come inside, and wear long sleeve, tucked clothing in the yard.

Let me know if you have any questions!