I would recommend looking for wholesalers in the area or send postcards to Multi-unit owners that might be looking to sell.

I will most likely go with postcard, postcard, letter, then corporate. 

Also if you don't have a company or LLC name, do you put your actual name on the letter/postcard?

I am currently working on my marketing plan and designing my postcard campaign. 

Keep in minds, you're probably not the only one hitting them with a postcard so you have to find a way to stand out and be willing to do what others don't... 

Feltus also explained that “Postcards are substantially cheaper than yellow letters” and therefore postcards allow one to “cast a wider net with” one’s “marketing budget.”

Most times if you buy a list, it won't give you a phone number, so you'll have to mail a yellow leeter or postcard to them multiple times probably before you maybe get a response.

Either call them up (you can find a lot of numbers on www.WhitePages.com, but not every number), or send them a direct mail sequence offering something of value, just to get them to contact you.I never door knocked, but it would be better than sending a letter or postcard or package.Also, search expired listings from 3 months ago, 6 months ago, a year, etc. 

FWIW it's all about the list.Letters, postcards, handwritten or typed.

It will take you a while to get traction but if sellers are coming to you (inbound) the likelihood they are motivated is much higher compared to you blasting out postcards and yellow letters (outbound).