Marshall, you and I must have been separated at birth...a very long time ago.
Your question has no real answer! When I was in school, oh so very long ago, I was taught that only the first, last, and most important words are worthy of upper case. In the end, you should be able to get a sense for the title by reading only the capitalized words.
However, I noticed a few decades ago that most song titles on CD's begin each word with upper case. This makes me crazy, because it is "wrong" according to the way I was taught.
Below is a link to a guide that I think you and I will agree, matches the way we were taught.
Good luck, and when you're done, I have about 5,000 song titles on my hard drive that need your keen editorial eye. :o)