I see marketing as a long-term investment. It takes time to establish a position in the market where others see you as a trusted authority. It helps to have a niche and to develop a unique point of view.
One way to build trust is to find a place where your customer hangs out and post helpful content there regularly. Also, think about what signals your customer might consider when evaluating a contractor. An open source project with many stars, followers on your social media accounts, qualified testimonials, a blog with quality content, etc.
Your best results will come from combining networking with a solid online presence.