Do you know anyone in the trades? If so ask them who they would use. When I was contracting my best referals were from others in the trades.
And I still go to my friends who are active to get referals on who to use for what.
Get a list of jobs they have done and go and see them, talk to the home owners, they will be sure to let you know the things that they think went wrong with their job.
Best advice is to know what you want before you talk to any GC.
I always hated it when someone would call and not know the basics of what they wanted.
Do you want 2x6 or 2x8 walls
What roof pitch do you want
How many doors
How many windows
How tall
etc...
Then you need to consider all the finishing, if you aren't doing it yourself.
Personally if I were to have one built right now I would go with a local garage company for the shell, the one that I would use has a great flatwork sub and has a good contract that lists all the materials and work to be preformed by the concrete sub and their own guys.
Itemizing the materails and the work leaves no room for misunderstanding by either party.