I have to start with a confession. When we started foster parenting, I really thought every Christian should do it. After all, the Bible tells us to take care of widows and orphans, and there are plenty of orphans who need homes, and I heard other preachers say things like "if one member of every church in America just took in one orphan, the problem would be erased" and I (pretty judgmentally) thought every Christian should do it.
I still think every Christian needs to be about caring for orphans and widows (otherwise, please go ahead and tear James 1:27 out of your Bibles and/or admit that you don't consider the Bible authoritative), but I don't think everyone is called to be a foster parent.
The county offers good training, but it falls painfully short of what is actually needed training for what happens when you open your home to a child. In fact, it doesn't prepare you for the hardest parts: what happens when the county lies to you again and again? What happens when a child is damaged far beyond his young years simply because he was left in a toxic situation (or returned to a toxic situation from a foster home)? What happens when a child knows much more than he or she should? How do you guard your heart against the moment when the county moves the baby you daily commuted to and from the hospital to visit, stayed up with at night, changed countless diapers, and fell in love with? How do you know what services are available to foster parents when nobody seems to know (and none of the services are linked, and none of them communicate with one another - and communication within the agency is terrible as well)? And the realization that the foster parent has no say in the most basic of decisions (a foster parent is not even allowed to give a foster child a haircut without agency approval - so when there's a life-or-death surgery, you'd better have an emergency phone number handy - they're probably not going to have one on their answering machine).
This isn't to say that we're done foster parenting. Quite the contrary. Because Jesus calls his followers to deny ourselves, and that pretty much defines parenthood (I don't care if you're a birth parent, an adoptive parent, or a foster parent; parenting is all about self-denial) and if you haven't learned humility, foster parenting is a quick study on it. I feel for the county agency, always strapped for money, and for the caseworkers, daily forced to make difficult decisions, never having full information, and having unbelievable caseloads.
If you are called to be a foster parent, get as much education as possible, and get in there and love some kids. If you're not called to it, don't. But that's no excuse - find out some way to care for orphans and widows. They need it, and God calls it true religion that God loves.