Mostly, I don't. Building an audience doesn't feel relevant to my work. It does nothing for getting me into juried exhibitions - I still need to do that myself. It can be actively detrimental to selling photography as you now cannot claim exclusive rights to a photo once you have published it. Even for portrait and event photography, most business comes from word-of-mouth, not people searching online for photography portfolios. Etsy jumped the shark years ago, with success there being more about marketing than your artistic skills.
In short, I am completely content keeping my work offline. I do post some photos to my personal site just for documentation purposes, but not my best work. And to be fair, I don't try to make a living with it. Someone trying to be a professional artist may very well want more online marketing.