I'd love to write a long post about all the different ways one can dig up great general contractors but the reality is that if you're looking for contractors you most likely need them NOW. I see questions everyday relating to general contractors: finding them, negotiating with them, trusting them, and always the terrifying horror stories.
I've found that the FREE, easy, and relatively fast way to find general contractors is to go to your city's website or office and ask for theirs. That's right, your city keeps a list of registered contractors. It's really that simple.... I've yet to find a city we've done business with that doesn't keep a list of all the registered general contractors they've done business with. In Chicago, where I do business, you can go to their website here: Chicago's Registered General Contractors and find a MASSIVE list of all the contractors that are registered with the city. If your city doesn't have them listed online you can probably call or stop by in person to acquire a very similar list.
What's great is you can literally run down the list calling all of the contractors till you find one that fits the bill. I'd suggest you call as many as it takes. Some only do large projects, $500,000+ and some only do small projects. Call them up. Tell them about the work you need done or the work you might need done in the future. Ask them to send you some examples (better yet addresses so you can check them out yourself) of work they've done in the past. Ask if they're willing to give you the names/phone numbers of a few past clients to get some quality references from.
It's literally that simple. In a matter of hours you can have a list of 10-20 experienced contractors who have done work you like and fit the project you're looking for.
Hope that helps with finding General Contractors!