If you like most people require a service at your home, especially a larger service like a major overhaul, its important to have multiple choices. Choices allows you to pick the right company for the job and get the most value. Making a list is very important, you can choose from the list since you can filter down a list to narrow it to specifications that suit you.
Some important tweaks to a list if reputation, reviews, how local and how long in business. You can create a list by asking some friends and neighbours and manually going through it. You can also go to some online listing placings and filter it down there as well.