How long has this company been in business? The longer a deck contractor has been around the more likely they know what they are doing and less likely they will disappear if things go wrong. Established deck builders have systems in place to manage jobs from beginning to completion. Veterans will be less likely to run into problems pulling permits, ordering materials, building the deck and making you happy at the end of the day. There is a learning curve for deck building just like anything else and there is no substitute for experience. You may need to pay a premium if you choose to go with an extremely experienced contractor but it may be worth it to put your mind at ease. If you are dealing with a salesperson representing the company you will want to ask about the experience level of the actual carpenters that will be doing the construction. Once again the more experience the better, the lead carpenter in charge of the project should have at least a couple years under their belt.