The fact that you are 31 and have no clue does not bode well for you. By the age of 19 I was well versed to the ins and outs of the music world. The chances of you having a high enough quality to your vocals and playing as to warrant a recording contract are slim to none. But if you are set on getting started, first off be ready for more rejection than you ever experienced in your life. More than you can imagine, so be ready emotionally for that. If you can't take criticism then you are in the wrong business. People will chop you up and spit you out to the point of absolute cruelty. They are not nice and don't even try to be and don't care. The first thing to do is to get together with someone who owns a small home studio and have them help make a 2 or 3 song demo. Then try and get some feedback from musicians that play for fun or to make some money. They will be mostly honest with you and say if you have an talent. Never ask family or friends!!!!!!!! If you watch American Idol there seems to be a theme of people thinking they are much better then reality dictates because of a positive bias toward them. You need an unbiased assessment by experienced people in the music field on how to improve and move forward with your endeavor. The average person has not a clue and does not have training in terms of what to listen for and look for in a recording star. Most people cannot get a true idea of how good they are. Singing in front of family and friends will give you a false sense of this. Get to some open mics and perform in front of some people to gauge just what level you are at. People that don't know you will be more inclined to give you an honest assessment. Be careful of people that say your great but laugh at you behind your back, there are plenty of them.

You're never too old to try. Granted, it's not music; but Samuel L. Jackson didn't get his big break until his 40's -- before that, his biggest claim to fame was being Bill Cosby's stand-in on "The Cosby Show"... As to recording a demo, I imagine that whom you send the demo to is a lot more important than where you record it. But you do need to get out there and get some public exposure -- performing at local functions and talent shows, sending that demo tape to record companies, networking with other musicians, etc.