Start with as small a sample as you can and make sure you can track the results with either a website to visit or a phone number to call. 

Things here have been slow to recover, but they are getting there, and I am already starting to see more and more visitors here in Fajardo. 

I go doorknocking in NJ, CT and NY...not exactly areas that are receptive to surprise visitors!

PPC: long tail keywordsSocial Media: Re-targeting old site visitors. 

We send out at least 2000 postcards per month and it takes us about an hour a month.I also agree with him to a point about the PO Box, but I still recommend that you use a street address if you can - but definitely NOT your home address - that can lead to unwelcome visitors - ask me how I know that!

During the lease you can charge them from their SD on a repair that was caused by the tenant or their visitors if your repair the problem.  

Has anyone ever bought without doing a site visit, or does any have any general thoughts on this?

Is it near a place that would attract short term visitors?

I pay yearly for my REIA, and I've seen others where it's $20 per visit or so to pay for the room and coffee/food etc...Being apart of your local REIA is a GREAT and one of the best ways to network with other people in your own back yard.

Etc.Clearly state rules in your lease about visitors.