All methods work. End of story. It is really what you are comfortable with and how much you want to spend.
1) Buying a list and cold calling: cheap but time intensive. Can be outsourced overseas. But in my area there is a lot of racism with older sellers and not being local or having and accent has almost killed many deals I had to save by coming in as the local yocal. You also have no idea of motivation usually.
2) SEO: You know you are getting a motivated seller because they sought you out. This can be pricey to maintain a high ranking on popular keywords and you never know when Google may change their algorithms. Easy to start getting into with sites like Lead Propeller or Carrot or Realeflow. But to be a star you need regular management and updates.
3) Pay per click: Don’t sweat native SEO and pay for ad space at the top of native rankings. It seems (our experience) people don’t seem to care if it is an ad or native. Can be pricey but unlike DMM you know the person has some motivation.
4) Facebook: Can be cost effective and gives you tons of tools to target people specifically. We don’t do much here but I know wholesalers that only market this route.
Side note: For all online intake you need a way to follow up QUICKLY. The chance of getting in touch with the person drops off ridiculously fast from when they fill out all your forms.
5) Direct Mail: Tried and true. Only as good as your copy and your list. Repetition works. We had someone get 52 letters from us once before calling (and selling). Average is 5-7. I know some people with good campaigns get 3-4% response rates (so 30-40 calls per letter). Ours is rather horrible at around 0.3%. So you can easily see the difference in targeting.
6) Bird dogs: Guys that get paid to tell you when they find homes that meet your criteria.
7) Networking: This is probably the all time king and covers so much. From going to your local REIA to telling your mailman you will give them a finders fee if they let you know about any vacant homes on their route and you buy it. The more people that know you buy homes the more opportunities just show up at no cost.
8) Driving for dollars: This one is great for finding those houses that obviously are ugly. Peeling paint? High grass? Shrubs not trimmed? Shingle missing? All have distress and lack of care. Now what you do with that house is the question. You can put a door hanger on their door or a flyer in their mailbox if you are non confrontational and then add them to a DMM campaign. Like to talk to people? Go knock on the door. Somewhere in the middle - skip trace the owner and hand off to a VA to cold call.
9) Awareness marketing: Billboards, TV, Radio - these can be great but you need to be careful because you can drive people to competition accidentally. How? Say you have a billboard that says “Sell Fast in San Antonio to Bob” - someone could just remember ““Sell Fast in San Antonio” and if you are not paying for pay per click or in the top 3 on SEO then you likely just sold the guys house to a competitor.