when I first started my main blog I didn't know about this community and so I didn't try to 'actively' promote my site or anything like that. Then my only visits where from my signature link on a webcomic forum I somewhat followed and the usual random visitor. After that I let my site 'die' because I had no other option at the time.
Now, starting from scratch (new address, etc) in about 2-3 weeks that I'm running it I'm getting about 20-25 pageviews/day some of them returning visitors (according to statcounter) and a little more on days I update the story. I've also started a new blog that has only my current novel (whereas the main blog is more like an archive of all my works). In ~10days it has about the same traffic that my main has, forcing me to think that having only one story/blog makes it more accessible/less intimidating.
That is ~30-35 (not counting the redirects from one blog to another) pageviews/day for me. I've never advertised either of those and I think that I'll wait for such a thing until I manage to create a somewhat bigger archive for the current story (I'm thinking at about 25 chapters at least), and they got no reviews or links from other places (at least that I know of), so I wasn't expecting much more than that.
About the forums thingy, I read 4 web serials and over 15 web comics, and I've went only to 1 forum of those (and that only for a limited period where I had ample free time). But I don't think you can compare forums to a tagboard. I've never posted to a tag board before and neither I'm inclined to. That is because while on one hand it offers me much better accessibility than a forum, on the other it seems totally chaotic and not structured, with no 'real' purpose. To put it simply: why and what should I write there? If I had an observation for the novel, or a comment for a chapter, I would simply comment on the comments form that has the plus to be more 'permanent'.