Attracting developers and community
There is only one main and foolproof way to attract users (who then might become contributors and developers): make an Open Source project that is attractive and compelling. Make a product people want and do it in a project that makes contributors want to come and to stay around and help out.
Contributor prospects will initially come for the main features and functions of your project, but they will not stick around and help out if the "softer" areas of the project are not also "attractive" enough. What license is used. How high the bar is set for getting started to contribute. But also what language is used – both programming and spoken. And when it comes to spoken or written language, it means both which language as in English or Spanish and in how the specific language is used in issues and discussions and more.
Attracting contributors to a project is about marketing, but you cannot lie. You really must deliver on what you claim about your project. By making your project appear as nice as possible – because it is – you increase the chances of finding users and contributors.