Good content should be:
- Authentic.
- Helpful.
- Human.
The idea here is that good content is all about the reader. Good content should be written for a very particular reader (for instance, you wouldn't write content that you want to do well for both enterprise PMs as well as developers, because you'd end up diluting your message to both). The idea is that your content should be genuine and authentic. If it's something that your target reader wouldn't find useful, maybe you shouldn't do it?
Another thing is that content shouldn't be self-promotional. It should instead be educational / helpful to your target reader. So for instance, if a lot of Stormpath developers are having issues understanding how sessions work, then writing an article which explains how sessions work in depth is a great way to genuinely help a developer trying to figure this stuff out, and gains a lot of brand awareness / goodwill.