Ripped from Pronet’s blog (all 5 tips are good):
Teach don’t sell
A lot of people are starting to blog because they want to make money. There is nothing wrong about making money or even blogging to make money, but try not to make a sales pitch in your blog posts. If you try to educate and teach people through your blog, it is possible that people will think of you as an authority in your industry which can lead to all kinds of great opportunities.
If your blog’s sole purpose is to make money, readers will know and will shy away. Blogging to better oneself and one’s community will bring with it trust, credibility, and possibly/probably business. Relationships are built on trust.