This is a multi=pronged answer. There is no "best" way, but rather several good ways. Take action!!!

1. Post lisings on Craigslist (there are many other online sites to use too)
2. Start a letter writing campaign to owners
3. Bandit signs
4. The town assesor's list
5. Housing court summary process list
6. Newspaper ads FSBO (for sale by owner)
7. Foreclosures Liz Pending lists
8. Probate court listings
9. Divorce court listings and divorce attorneys
10. Business cards that say "We Buy Houses/Apartments" (I like apartments better)

What are you currently doing? What is working? What is not? I'm sure others will add to your post with some great ideas. Chime back in to let us know how it is going for you.

-b