I really wish my dad had talked to me about girls. Not the birds and the bees bit, but about how girls and boys are both the same: afraid to get their feelings hurt, unsure how relationships should progress, often hurtful to others by accident. He could have explained that the easiest way to let someone know you like them is to smile and say "Hi" every time you see them. To not be afraid of physical contact like dancing or holding hands. That even if you say or do the wrong thing, make an embarrassing mistake, if the other person likes you they'll still like you afterwards. That a good first date involves just spending time together talking and getting to know one another (and that I should therefore avoid movies for a first date!) It took me years to figure that stuff out, and looking back I can see a dozen points in my life where a simple explanation from my dad could have opened my eyes and saved me grief. Thankfully my wife recognized that I was clueless the moment we met, and simply told me how she felt.