Originally Posted by GreenI.A.
As far as "lawn care" vs "lawn service". I'm not sure about in your area, but in many areas, "lawn service" is what many people think of as landscaping, such as mow-n-blow. Where "lawn care" is generally more of the fert and chemical part of the industry.
Green brings up a great point. Do some Google searches for the competition in your area using "lawn care" and "lawn service". See what pops up. Then, if you're up for it, register for a Google AdWords account and use their keyword search tool to see what term people in your area are most searching for.