Use the search function here at BP on these topics:Develop a list for marketing, if using direct mail.Market for motivated sellers: direct mail, seo, bandit signs if legal in your area, car wrap, cold call, door knocking.  

SEO, Facebook Ads, Google Ads, Email Marketing, Content Marketing, Social Media Marketing, etc).

Working on SEO and getting better rankings.

Make it credible, get a logo, take awesome pictures of you with your logo, set up your google my business, verify your site with Google, and look like an actual serious company.Once your site is credible, do your cost/deal calculations for every marketing option you are considering.Then pick one and allocate the appropriate funds to said marketing option for you get one deal (that is why you calculate the cost/deal, so you know how much money you need to make one deal).You WILL make a deal ... that is the purpose of the cost/deal calculations, to remove luck from the equation, and dump that money you made into SEO and further marketing.You keep doing this till you have enough funds to start scaling your business.

I've heard good things about SEO but have no experience with it and knno little about it. 

Improve their website SEO.

Facebook ads, Yourtube ads, SEO,  THAT stuff works reliably.Have no money?

This means FB ads, Google Adwords, posts with links, SEO if you want to take the time and you want to wait.

I would move away from cold calling which is a fine way to get leads but it should be just one of the lead channels not the only one, as it’s not easily scalable and I would try to generate incoming leads with SEO or by converting some of those leads to listings and generating referrals from those, so that your business can grow and start to run itself without having to basically become a call center (unless you want to run a call center business).

BECAUSE SEO usually takes time.