Hope you're launch was great! You'll want to build a marketing strategy aligned to targeted users who are most likely to adopt your app/service. Without a budget, your greatest resrource is human labor - you. I can help you learn how to organize your marketing plan with some primary and secondary research, setup a basic, effective model and an implementation plan that keeps you organized as you execute tactics. From there, it's a matter of analytics and understanding which channels (strategies) to spend your time in.