How to find good subs

I'm fairly new to the business end of this. I do mostly carpentry work myself. Framing, finishing etc. I would like to work towards larger project where I would like to sub work to masons, and roofers. I am at a loss as to how to find and work with subs. Can anyone point me in the right direction.
One of the big reasons I went into business is from hearing from people that they were burnt by this contractor or he never finished the job. I don't want to ever get that reputation and relying on a sub is scarry. I know there are many many good contractors out there but don't know any myself. How do I find good reliable subs to work with and how are they paid.
Thanks for any help you may offer.