@James Taylor I would recommend sending handwritten letters out to lists in your area with multiple levels of motivation (I pull lists from PropStream). You can buy Forever Stamps for these letters on eBay for cheapest (about $0.42 per stamp). As for the letters themselves, try to get colors other than white to stand out in the mailbox and make sure you repeat every 3 weeks for up to 7 touches. I have heard it's best practice to match the color of the envelope to the color of the cardstock.
Write simple messages on these that don't scream, "I want to take all of the equity in your house." This is all about putting in the work that other people don't want to. Regurgitating the same sort of buzz words that everyone else uses ("close fast," "all cash," "as-is") probably won't give you the best response rate starting out. Remember that you are a problem solver for the person who needs to sell. If you have a mentality that puts that other person first, you will naturally make more money anyways.
It's all about consistency, and making sure you have a strong "why" because you will get slapped in the face many times.