From my own experience: search for blogs of favorite writers, observe aggregate sites like Hacker News and Reddit for authors with a style that resonates with you (subreddits of niche topics are often surprisingly rich in a good content), search for niche topics that are of interest to you, ask friends about any interesting content.

Its organic discovery. Some I come across in HN discussions. Some I find while googling stuff. Since my interests aren't mainstream, most of the blogs I come across this way are interesting to me and I subscribe.

These days there are few awesome lists or the like for curated, sorted and tagged personal blogs too. Its a great time to start with RSS.