I run some blogs with SEO on particular niches which I frequently update and rank fairly high for particular framework issues. I don't want to get into details, but companies google these issues, find my posts, fail at solving them with the steps which are very clearly laid out by me, and then reach out to me to see if I am available to fix their particular issue. That is about 30% of the clients that I get. The other 70% are past employers or clients and references through past clients and former colleagues.