10. Your conquest count
Look, you know how many chicks you've bagged and it's probable that some of your friends do, too. But that's where this circle of info should close. It's not necessary to give your current lover a running tally of conquests. Sure, you both want to be safe when it comes to sex. And I encourage you to get yourself tested to prove to both her and yourself that you're clean (of course, she should do the same). But there's no need to divulge numbers — doing so will upset her and put you at risk of spending the night alone.
9. Your income
As a relationship progresses, it is natural that a couple grows familiar with each other's finances. But in the early stages of dating, there is a very sound and reasonable argument for playing your personal monetary value close to the vest. Two words: gold diggers. You could have the bank account of Donald Trump or the debts of Mike Tyson; either way, she shouldn't know. Let her dig you for you first. Then, if you're flush, you can buy her the stuff she likes and such. And if you're broke, she'll either ditch you because you don't buy her stuff, or she'll prove that she's a worthy character by sticking with you. So keep your Benjamins to yourself.