@Luis Magnus,
There are a lot of ways to market. @Jerryll Noorden is a genius in the arena of website SEO. And there are all of the other things he mentioned (D4D, DMM, Cold-Calling, various lists, and on and on and on).
Here's what I suggest. Find what works for YOU! If the phone scares you, you probably shouldn't do cold-calling unless you make it a personal goal to get over it. If you don't have the funds to sustain a DMM campaign, then don't bother - or find a way to get the funds. Then, once you find what works for you, dive in, petal to the metal, and do not stop. Do not slow down. Pass Go like it wasn't there. Put all you can into it and then some.
That's marketing, but you also need to work on education and networking.
There are a ton of podcasts out there about wholesaling. I like Wholesaling Inc, the BP podcasts, and I just subscribed to the Real Estate Investing Mastery Podcast (I don't know much about this one yet). I spend a lot of time in the car, so it's a great opportunity to learn and get some motivation. There are also books. (Again, I like Audible because of the driving). I like the books, too. I just finished, "If You Can't Wholesale After This... I've Got Nothing for You", and while I disagreed with a couple of points, it was overall a great roadmap.
Now network. Go to local REI events (meetups and REIA meetings). Get to know the local REI community. They can help you learn and they are going to be where you find a lot of your cash buyers.
Have fun, and good luck!