Personally, I find it’s really not too complicated of a process. When writing an email or blog post, I try to think of a subject line or heading that would instantly make me click a story, or open an email. I can look through emails and stories that I have clicked, and re-engineer a headline based on the same principals. For me, those principals are usually relevance to projects I’m working on, and time investment to process the article or email. Off the top of my head, I’d be hooked by “Top 5 WordPress plugins for designers” or “How to build an events engine in PHP”, or “Quick, professional masking techniques for After Effects”, etc.
For more info on the science of subject lines and headlines, check out these articles:
Email Marketing Subject Line Comparison (ironically a non-compelling headine IMHO)