You must have to clear between graphic designing and marketing, both are playing own role, marketing is the root of the company, if you build your empire but no one knows what actually there, you must have to clear what kind of project you build who can afford and what class of people are afford it. 
There is no big science to making effective graphics or post for the real estate there all about what do you offer to customer for tethering customers you must have strategy and planning 

there are so many levels of doing real estate markeitng

Level 1 building a first class website of your project

Level 2 Collecting investors database

Level 3 work out or filter on that data

Level 4 Shoot broadcast messaging 

Level 5 Prepare dumpy project

Level 6 Create social media 

Level 7 Video Ads