Depending where you live, just search a few in your area and then search reviews for that company. That's about the best way or ask someone who has had some work done by someone and see if they are happy. All these companies have online reviews. If it's available in your area, you might start with Yelp.com as they have loads of businesses and people's reviews of the work done. I used to be an online tech a few years ago. Shame you didn't say where you live as I could probably refer you to some good people.