Are you worried about not having anything to talk about? about not giving off a fun/energetic vibe at a party? I think I know why that is. I am by no means an expert as I am still a virgin. But this is what I've noticed lately.

People who are charismatic are capable of always finding something fun to do no matter what the situation is. Have a lot of work/school thats overwhelming? That subconsciously reduces your positive vibes. What you need to do is find a fun interesting hobby or an activity that you genuinely enjoy and find time to do it at least weekly no matter how busy you get. Its important for you to find some sort of mental release during stressful times.

Back home from college/grad school and have nothing to do? Thats not an excuse. That sounds boring. Do something that makes you a better person. Go tutor some kids and teach them programming. Do it for the intrinsic rewards. This doesn't seem like it will have a direct benefit to your game, but it subconsciously adds to your inner game/personality.

Your personality/charisma/positive vibe/game is like a plant. You have to continually water it. If you stop feeding it, it wilts and decays.

Like I said, I just had this epiphany at a party after talking to this dude who did all these things. Now I am slowly trying to live by this. Hope this helps!