Know-How Exchange : Website Critique

We are a lawn care company providing lawn mowing, landscaping and lawn treatments(fertilizer etc..). Our target area is homeowners in about 15 zip codes in/near Fairfax, VA. www.mowcow.com
New clients call us primarily because they see our cow-spotted trucks in their neighborhood, or they received a mailed coupon or word of mouth. Our logo has changed (cheesy smiling cow now) and I'm about to update the website. Our goal is to greatly increase new clients via our website througout the whole year--not just in spring when grass grows fast. I want our site to rank when clients in our target area search for a lawn care provider. Where do I put those keywords? I need a super duper call to action. How do I get others to talk about us in their blogs? How often should I change the content to keep it interesting?

I'm not a web designer and I'm very, very appreciative of all advice from you experts.