When someone is looking for a product or servicess they have lots of choices. The challenge is to convince them to pick you. They way to do that is to use your blog to educate and inform. Use it to share your knowledge and expertise. If you blog this way, your potential customers will see you as far more credible that your non-blogging competitors.
Sometimes I run into people who say, "If I blog to educate and inform, then I'm giving my expertise away for free and no one will hire me." Nothing could be further from the truth. You have far more knowledge, experience, and judgement than you'll ever be able to put into a blog. Your blog merely gives them a glimpse of what you can do for them.