I'm coming from a business/economics background thinking of starting in real estate in New York City.
I've never sold real estate per se, but my brother is a home builder and started his own brokerage firm - so we've talked a lot about marketing his company.
The #1 thing he's realized is it's ALL world of mouth and relationships. You can't advertise your way to success in real estate. You need to be the person people think about, trust, and refer their friends and family to help them with their real estate needs. That means it takes a while, unless you do a few things.
1) Write a blog for your customers / write about the neighbourhood and things that are important to people buying / selling houses.
2) Do a video blog / podcast on same topic
3) Host free information sessions and teach people everything you know about buying or selling a house. Give it ALL away for free. Be sure to give them the good stuff, the secret tools, services and tricks.
4) Spend every night of the week at social events trying to find ways to help everyone you meet expecting nothing in return.
That's what my brother did and built a multi-million dollar company in 5 years. He's the master.