When offering to give a referral, make sure you give the contact information of someone you trust. After all, your name is the one attached to the referral. You want to be known as a person who values quality, and a bad referral can tarnish your reputation.
Whenever possible, give two or three referrals. This shows that you are well networked. And, if you have time, be the one who does the introductions. A little credit goes a long way.