There are a few previous discussions floating around [0,1]. A good rule of thumb is to submit your stuff only if you think people here would find it interesting (the same as any other submission). It'll be a normal article submission, not a Show HN or something (as per the rules in that section). If you have enough of a following you might just wait for them to submit your blog posts -- serving as a bit of a natural filter for what other people think is a good fit for HN.
Personal blog posts land here all the time. I wouldn't hesitate to submit your posts! So long as it's not naked self-promotion, if the content is good it'll get voted up and gain visibility.
Assuming the content is relatively novel or fresh and possibly niche (tech related) for example.
I hate spam, so I hesitate to submit anything here. Perhaps it’s the fear of critique that induces hesitation (for me personally).
Is there a general rule of thumb or guideline?