Who are your early adopters? Write 1-5 different types of early adopters, and each on their own line.
These are the people that will not mind if your service has bugs because they really need your solution. These are the people that will evangelize your business and help you refine your solution. These are the first group of people that you should try to find.
You want to initially build your product for the early adopters, since you do not want to try to do everything for everybody. Again, you just want to solve that #1 problem really well - for 1 niche market. This is just to start it off. Once you are established with loyal early adopters, you can slowly add features to appeal to a bigger audience.
Wantrepreneurs have full time jobs, in their 20-40s, and visit Hacker News
Wantrepeneurs who ask about Lean Startup questions on Quora
Incubators who want to get earlier access to promising startups.