I know how you feel - I wrote an 'anything and everything I've ever found interesting' type blog for ten years, and hardly anyone read it (despite a pagerank of 4, and certain individual posts on obscure topics getting decent traffic via Google).
This year I set up a tightly-focussed, single topic blog and committed to writing three posts every week day - it took off, I have lots of enthusiastic readers (and this month I paid the mortgage with a single Amazon affiliate link, if that matters). I did no SEO beyond writing clean, simple HTML, and actively ignored some standard SEO advice (eg. one-word titles, no repetition of keywords).
In other words: in my experience you're never going to become the next Kottke with a general interest weblog, but if you find a niche you're passionate about, you don't need to do any SEO douchebag stuff to attract readers.
The link's in my profile (not sure what the rules on self-linking are here!)
I get between 45 and 50k page views a month, which isn't exactly crazy traffic - I think the affiliate link in question did well because it was a) part of a very enthusiastic review of a pretty obscure product and b) the post was linked to/reblogged on Tumblr by much more popular sites.
It's certainly made me rethink my plan to put adverts on the site - hard to say without testing, but past experience with Google Ads makes me think the occasional hardware review/affiliate link would be better for me, in terms of earning some cash for all the work I put in, and better for my readers (no intrusive ads, and a good post is a good post whether it has an affiliate link in it or not).
This year I set up a tightly-focussed, single topic blog and committed to writing three posts every week day - it took off, I have lots of enthusiastic readers (and this month I paid the mortgage with a single Amazon affiliate link, if that matters). I did no SEO beyond writing clean, simple HTML, and actively ignored some standard SEO advice (eg. one-word titles, no repetition of keywords).
In other words: in my experience you're never going to become the next Kottke with a general interest weblog, but if you find a niche you're passionate about, you don't need to do any SEO douchebag stuff to attract readers.