Landlord credit/reference check

In the past I have always used brokers to rent out the vacant apartments in my building, but I always felt bad about the hefty (15%) broker’s fee the tenants had to pay. Now that Craigslist has made it so easy, I am renting the apt. on my own. My question–how do other landlords run credit checks on prospective tenants? Thanks, in advance, for the advice.