With a myriad blogs out there, I assume it's difficult to get your blog noticed.
Is it easier to drive traffic to your blog than to drive it to your main website? If yes, is this because search engines prefer sites with more "meat" (text) in them?
For instance if you were selling a service that does online analytics for the music industry, write posts about the music business using the data you collect. Include relevant keywords such as 'online artist tracking' 'statistics for band', etc. Those keyword phrases revolve around what potential customers would be searching for in Google when looking for a service like yours.
Outside of organic results like above, drive traffic to your blog by producing content that is meaningful, useful, and interesting to your readers. You want your content to have value to your readers.
Join the conversation on other blogs, through commenting. IMPORTANT don't spam..add value.
Tell good stories.
Check out http://www.mint.com/blog/ the used their blog expertly all the way through their exit and to this day.