1. Choose your vertical (wisely)
2. Deep dive into at least 50-100 web sites / online presences
3. Begin to recognize patterns
At this stage you should be ready to analyze your findings. Essentially you'll discover there are key components that every player must have. And typically its around digital content curation, inbound marketing, etc.
You can strategize two ways. An indirect approach, where you begin to publish your analysis in the form of blog posts, whitepapers, etc. And let potential leads find you.
But I think I prefer the direct approach. Cloud computing / SaaS is a great example. There are myriad events right now. For example, enterprise-scale such as AWS:reinvent coming up in Dec. But also smaller ones, such as Slack's inaugural SPec conference next month. You can literally generate 100+ quality leads in hours walking the show floor. Using your research and your skills, be specific about where a company may be weak, and what value you can help them realize.
You can open a conversation with something as easily as, "Hey, I noticed you still require a call to sales to make a purchase, have you considered an online storefront, I happen to have some Stripe API integration tools I built for my own site that can help..."
Best of luck ;)