Most bloggers ignore two important points:
Most blogs aren't promoted, they're not a part of a community and they don't encourage/attract followers.
Obviously good content is key. This is the whole idea.
But you need authority, which comes from links and trackbacks you get from the web and the wider blogging community. You'll have to join and connect and engage with people, unless you're a well known personality/celebrity.
So things like Blogger, BlogCatalog, MyBlogLog, Technorati, Irishblogs etc are alll good places to start.
Relevance: Blogs can have great search positions - but most newbies have a splattergun approach - posting for everything from soccer results to reviews of electronic products to private rants. That type of blog, unless its incredibly insightful, funny or intelligent will probably just serve as a hobby horse.
If you had a proper "theme" and you focused on that theme - e.g. Pony Trekking and each post covered different aspects and events in the life of a Pony Trekker - chances are that it will rank for searches related to Pony Trekking. Posts that cover everything fromArsenal, Greyhounds, cars and Kerry Football are unlikely to rank for anyhting and certainly wont rank for "great blog" or "funny blog" etc.
Traffic doesn't come by accident. Its worth remembering that when people first discover a form of technology (like blogs and twitter) and learn to use these tools - they (naturally) get a certain sense of great personal satisfaction and achievement. Little indicators that they get some traffic or PageRank (which isn't related to SERP's btw) quickly leads into the self-belief that they are now internet traffic and marketing whizz kids and billions of people will now follow suit and read their blog which will generate gazillions in revenue from Adsense and Affiliate sales following a twitter account that reads "Internet MArketing Guru and Social Marketing Ninja" with 119,000 followers etc.
The internet is too full of this crap .... sorry, the last paragraph was just written for my amusement and those of anyone else on the forum that has seen this developing