Too Much Information
You've known each other for all of one hour, and already you're sharing the details of your abusive childhood, your last five relationships, your political and religious beliefs, and even your latest doctor visit. For at least the first few dates, leave your intimate stories and emotional baggage at home.
Remember that you don't know a person on the first date -- or even the second or third dates. Not only are you divulging intimate details about yourself to a complete stranger, but by talking incessantly, you're also not letting your date get a word in edgewise. You can be sure you're not going to get a chance to stage a repeat performance on a second date.
Get to know each other a little before you spill the entire contents of your life, and give your date a chance to talk, too. Only by having a two-way conversation will you be able to figure out if this person is worthy of a second date.
Once you get to know one another a little better, you can start introducing more personal information (though you might want to wait on sharing the details of your doctor visits until you're married).