Lessons Learned Building Open Source Software (mitchellhashimoto.com)

++ for documentation. I'd say start with that first and think about how a brand new user will use your software. How do I install? What are the dependencies? Etc.

Good documentation can easily trump bad code and architecture.

I couldn't find "support the major operating system platforms".

That means my ten year supported version of Red Hat or Windows.

With no experience at all, I'd like to add a marketing lesson: if you write a blog post concerning your project, make sure it features an easy link to that project.