First, write well (I’m still working on this one). Listen to David Roodman.
Then get some decent tools. I use:
Windows Live Writer – Let’s you draft rich-formatted posts (with photos!) offline, and preview you them as they will look on your site. I just discovered this and it is awesome.
FeedDemon – For offline feed-reading. Syncs with Google Reader
Fire Status – Post to Twitter in 2 clicks. It sorts out the links for you and everything
Page2RSS.com – For monitoring sites which don’t have feeds