How Do We Ask The Right Questions?

This idea just came to me and it seems so obvious, but so many people, including myself, don't always ask the right questions when we meet new people.  I recently asked a guy what he does for a living only to find out he was currently unemployed.  Then, continuing to stick my foot even further in my mouth I asked if he had any kids.  The answer was no and they had been trying for a while.  I can definitely relate to that one.  My wife and I have been trying to have children for 14 years.  While it used to be a sore subject I think we've gotten used to the question and try to answer gracefully, but it leads me back to my question, how do we know what to ask if we're trying to forge new friendships without possibly offending anyone?  One book my wife is reading suggests that we ask if they would just mind telling us a little about themselves instead of asking for specifics.  While I like that approach I tend to be very forgetful and will probably not remember to think to ask that.  Once you find out about a situation someone is going through, how do you show concern without touching a sore spot?  I know a few people who are currently unemployed and I want them to know I'm praying for them but it just seems rude to ask "Have you found a job yet?"  Maybe a better way is simply to say I hope the job search is going well, and I've been praying for you.  I think the world would be a much better place if we all just put a little thought in before we spoke.  I know that I've done this to many people and I am truly sorry for anybody I've unintentionally hurt through these type of questions.  I think most people wouldn't tell you that it bothered them, but I still think it's worth trying to be more consderate.