On the second one (marrying someone that’s not compatible), remember that I said to make sure that she meets even the most trivial of requirements. I do not make any exceptions to that; if she is brunette, and you’re more attracted to blonds, either ask her to bleach her hair, or don’t get married. Even though it’s trivial to some (including myself), it’s not trivial to you.
The other fault that men tend to make is that they shouldn’t be so narrow minded about their committed partners. Her sexual prowess and physical attractiveness won’t mean jack squat when you’re divorced.