How do you build your audience/community?

I am intrigued by the indie philosphy and the independence (financial + creative) it offers.
However one key aspect to be successful as an indie hacker is to have a following/community/audience where one can quickly share the product (on twitter or your own blog ?) . I am referring to the pre-marketing phase where you share your product with your immediate network. Many indie developers (including me) who are just starting out don't have a network. How do you go about building your network ?