An SEO power tool
A blog is one of the most powerful SEO tools for start-ups. It's great for publishing content, generating links and also leverage for relevant reciprocal links.
Writing articles on your blog regularly that are of relevance and interest to your target market will definitely be a sure-fire way to bring in a stream of visitors to your site. Twitter/Facebook mentions are the first to come and the occasional links.
As a start-up, sometimes just sharing regularly articles you've written on your company Facebook wall, Twitter account and then resharing using your personal account is quite a good strategy to get the ball rolling.
Also, it's important to remember to set the blog url to http://www.yourcompanyname.com.au/blog instead of http://blog.yourcompanyname.com.au. The reason for this is that Google treats the subdomain prefix www/blog as two separate websites. What you want to do is ensure that any links going to your blog gives back to the domain authority of your main site. Albeit somewhat technical, this will make a big difference and I'd recommend it 99% of the time.
Finally, a blog is great for catching the eye of other websites in the industry. Say you want a link from XYZ site in the fashion industry. You could create a top five list of the best fashion blogs out there and put that on your blog. Then you can go ahead and contact these bloggers to let them know that they've been put on your list. A lot of the time, they would be delighted to know and will give you back some link love.