If you want to just walk up to your computer and write a good hub, you'll want to do a lot of research on keywords first. The other option is to just start writing a few hubs on things you are interested in and see what gets the most hits. It's the lazy way to do it, but of course it takes time.
To get real traffic to your hubs, post links in forums that discuss the content of the hubs. If the hubs are really good, active members on the forum mind pass that link along.
Yahoo answers is one place that I've used, since you can answer a question with a few sentences and refer the asker to your hub for more. And if you get the best answer, everyone who sees the question will see your link.