@kimoo - Speaking of blood, not all girls bleed when having sex the first time. There's many different forms the hymen can take and some won't bleed, some might, some do. Luck of the draw. Now factor this in- vaginal bleeding is usually caused by several factors- lack of lubrication because she is not desiring sex or not getting foreplay. Other reasons are the male being unusually hard, large and/or rough, a medical issue like dehydration, or being caused by birth control or medications she's taking. So it's a combination of the type of hymen and ALL the above factors.
I've accidentally caused a bleed with my current gf when we first went out. She's not a virgin and had a few boyfriends prior to me. Apparently it was the fact that when erect, I am HARD (can't bend it at all) and she was excited by it and went crazy with me. When done, I see blood mixed in and was like "Oh shit. Are you okay? I'm so sorry" and she didn't care- she was happy. From that point on, I've been reminding her I prefer it more gentle so she doesn't bleed. But every now and then, she goes crazy. Good thing is, she doesn't bleed anymore.
Every girl is different and they like different things. Your best bet is to listen, be respectful of her, and learn what makes her motor rev. It'll lessen the chance of any bleeding no matter her status or age. And increase her respect towards you.
Remember- Sex is give and take all at once.
