If you go to bid a job and it is to large for you to do or you don't feel comfortable doing it. Call a reputable company probably with a full page add in the yellow pages.
Keep in touch with the home owner. Make sure the home owner is treated right by this other company. You won't have a contractual obligation to the home owner but them knowing you are looking out for there best interest will keep you in there "word of mouth".
If a reputable company stiffs you on a referral. Learn your lesson, don't do business with them anymore and it's not slander if it's true so don't hesitate to tell others about the mishap. Only if it's true. If they tell you that you will get 10% of the contract and they don't give it to you and you tell the story, it's not slander. You won't get your money, but there will be negative statements circulating your area about them.
Another good idea may be to ask them to sign a written contract with you before you even send them to the home owner. That way you aren't sub contracting, the work contract will be between the other company and the homeowner, but you will have a contract with the other company stating what you are to make from the referral IF the proposal is accepted by the homeowner and the payment terms. (I suppose in a way that is subcontracting, just not as profitable)
I hope that was helpful, A little confusing but helpful