Hi,
I have rental properties in California as well as in Schaumburg. Here is the web site that I use to perform Credit and back ground checks: https://www.tenantverification.com. It's pretty straight forward and only cost $34 to do a Credit, Criminal, and Evection background check.
Although I require these checks from all rental prospects I do call the prior landlords and confirm employment and pay range with the prospects employer.(Most companies will not tell you over the phone what the employee makes but will confirm a pay range..i.e $50-60k a year).

Good luck!