I'm not in a blogring, although I would love to increase my blog's readership. I've gotten a few readers on mine just by leaving comments on their sites, and a few people I know through the blogworld have a link to my blog on their site. People slowly trickle in .... one of my blogs gets about 12-15 hits a day and the other gets about 5! I suppose it's better than nothing but I do sometimes wish it would be more!
Anyway, to start, if I were you, I would start searching for other blogs that interest you and leave them comments and see what happens from there! =)