Just write.
Seriously, the biggest problem that most people have with blogging (myself included!) is blogging regularly. From a traffic perspective, you'll want inbound links all going to the same site as that helps in general.
If you tag things well, that will solve 90% of your (described) concerns.
For successful blogs: Think of many news/opinion sites like HuffPo, TechCrunch, Forbes, and hundreds of others.