The biggest key to success in a new market is to have streamlined internal processes that are replicable in a new market. Will you be able to manage the company the same in the new area? What will happen for estimates? How quickly will you be able to address the concerns of a customer? Can they get the quality of service that your local customers get?
If your service diminishes in quality during the transition to a new area, things won't go well for you. Make sure that you've covered all of your bases before attempting this.