I have made some great hires over the years, and I have made some terrible hires over the years. One thing I have never regretted, however, is being committed to hiring slow. Hiring people is an art, but you need a system so the right people end up on the bus. Furthermore, you want people in the right seats.
Make sure they fit your culture (this has been my achilles heel).
Make sure there is chemistry (spend lots of time together).
Get referrals on their character (this is common sense).
Do your homework on their competency (see their previous work).