It's sad to see so many people here saying that social situations, especially with women, induce so much fear. Here are some tips from a geek who was in that position, learned a few things, and now has slightly less crappy social skills:

* Stop objectifying people: 'Objectifying' is a kinda intimidating word, but the meaning is essential. Stop making people objects in your mental model of the world; stop making them characters who play a role in your private theatrical narrative of rejection (and whatever else you've lived through). That big scary monster who might reject you - that's the object. The real person has their own entire private universe, like you, of fears, desires, perspectives, priorities, needs, worries, and theatrical narratives. They haven't read your script, don't know their assigned part, and most importantly, don't want to play it - they want to be themselves! You and your interaction play a tiny role in their lives; the reason they respond in X way likely has little to do with you; they may be as scared as you are. Instead, be curious about them - who is this person completely distinct from you? There's a vast universe of emotion and experience you know nothing about - so much to learn! Give them plenty of space and assume nothing because you don't know shit; the variety is unfathomable; if they don't surprise you, you're doing it wrong. More importantly, step outside yourself and care. Grasp that they have a hard time too - this mortal coil sucks for everyone - and be compassionate about it. Genuine compassion is your greatest tool; it also turns your attention away from your fears and outward to others, and you also do a good deed. Humans crave it. (I'm not blaming you for objectifying; I know why; it's hard.)

* Be genuine about your emotions. That is, be honest. You're not hiding them nearly as well as you think; people have evolved and learned throughout their lives to pick up very subtle emotional cues, consciously and unconsciously. (It's a matter of survival for the organism - 'Will the one next to me kill me? Feed me? Parent my children?') And here's the trick: If you aren't honest with yourself about your emotions, then obviously you can't be honest with others. Too many males are raised to treat emotions like a crippled, angry dog they're forced to feed - great, you just kicked out the strongest leg of your little table of stability and capability. Your intellect is not nearly enough to compensate, but you probably noticed that by now; your emotions are actually your best friend and tool - amazingly powerful and they also provide stability if you take care of them. Be emotionally genuine and honest or you're lying to the other person (and maybe yourself); people don't like liars. That doesn't mean you have to act out on them (yell when angry) or announce them at every moment or that you shouldn't have some composure (be able to manage them), but be honest with yourself and don't pretend. Try this: 'I'm such a nerd! Talking to people terrifies me.' That's genuine, shows you can be trusted, and allows them to genuine.

* Pay close attention to their emotions. Ask yourself, 'what is their emotional affect[0] right now?' and also, 'what is their unsaid concern, what is their agenda?' Yes, it takes effort and concentration to do those things while also paying close attention to their words. That's called listening. And it also makes you shut up, stop interrupting, and again focus outward on them and not on your fears or the game/work you're obsessed with. When people see and feel you do it, they really appreciate it; it's like magic. And you'll be amazed what you learn from other people when you let them talk.

* Back way the f-k up and give people (emotional) space, lots of it, enough that they can go anywhere in their conversation and not meet any resistance from you (an uncomfortable look, an interjection, etc.). Enough so that they can develop an incomplete idea or pause without at all worrying that they'll lose the floor to you. Give them freedom; give them control. If you're like me, that's hard; bite your tongue, literally if you must. And that means that if you get the emotional cue that they don't want to talk right now, then swallow your fear and respect their completely legitimate wishes. Your fear, your insistence that they respond as you want, is about that object in your mind (see the first point above). That's on you, not them; they aren't there to serve your emotional needs. If you give them space when they want it, you'll find that they trust you when they are ready to talk. If you don't, then why would they want to come back?

[0] https://en.wikipedia.org/wiki/Affect_%28psychology%29

EDIT: Some minor edits