Inform, don’t sell.
A blog can be a great business tool.
But if all you do is sell you won’t get many people to read it. Inform your audience about your products and services, but do it in a way that teaches something. Give them useful information that they can take action on, but leave them wanting more. If a product or service has 5 useful applications, give them 4 then invite them to contact you if they would like more information.