My dating advice. Never had a girlfriend. But have learned some things.
1. Become comfortable asking out women you find attractive. If you can't approach them in real life, that is not a good sign imo.
2. Don't worry too much while you are around her. If you are nervous, maybe that's healthy if you don't have a lot of experience. But if you are too nervous, she'll sense that and won't want to be around you. Lose your nerves. Say what's on your mind.
3. Sex is normal, bound to happen eventually if you are attracted to women and they are interested in sleeping with you. It's just sex. Don't worry too much. Use protection.
4. If you are interested in a woman and she says she's dating someone else, tell her your happy for her. And then leave her be. I was interested in someone and she told me this. I told her I was happy for her. I wasn't sure she was being honest but she didn't get back to me when I asked her if she was telling the truth. So I'm leaving her be. I'm happy for her if she's dating someone she's happy to be with.
5. Don't worry about what women think of you. If spending time on Letsrun is your thing, who cares.
That is my best advice.