Hahahaha....
I thought I was interpersonally retarded until I got an ENFJ girlfriend at 16 who showed me what I was capable of (ha, sounds hilarious when I say it). Then I realized I had been pretty good already.
It's all about telling the truth. And staying silent strategically.
And, making a good impression on everyone at all times, even if you don't care about them. Because it can come in handy later.
Note: Not a very good way to live life, honestly...it's totally a compulsion. But I at least always win the loyalty game. I can get anyone on my side if I need them.
Trust is built through being honest. And the other person believing you. The best way is to tell the truth, but selectively, because the other person will see that you're being genuine (which you are), so they'll trust you. Even the most "powerful" or "skilled" social visionaries know I tell the truth, because I do.
Don't give anyone a reason not to like you. If you sense that they might start resenting you, call it out right then and explain yourself. Look flustered. Look like you care that they like you (which has to be genuine, even if you don't like them).
Every word you say, every facial expression you make, all of that shit...those are all "moves" in the social game. They should all be profit-maximizing in terms of generating positive feeling towards you (with different weights for different people's feelings, based on how important they are to your long-term strategy).
Strategic aside: it's smart to disagree with people, too, or else they'll suspect you. So you gotta get in little arguments at strategic times -- times when even if you piss people off, it won't matter much in the long term. You don't want to come off as someone who will blindly agree. Also, say your opinions that differ from the norm as long as they aren't too threatening to those around you at the time. And you can't lie. You have to be willing to cause short-term discomfort to those around you, because it's better for your image in the long run.
Also, you have to take stands against certain people -- you have to be fair-minded. You should visibly regret the fact that you have negative sentiments towards someone, but hold your ground against people that have broken a moral code. You don't want to look weak-willed, because then people will know they can walk all over you.
The most important part, though, is -- DO NOT LIE unless you honestly have no other choice. It's basically cheating, and people WILL notice if you make a habit of it. Every emotion you show has to be genuine. You can and should make sure to present them overtly if they're profit-maximizing, and you should downplay them if not.
Anyway, this is not what I recommend, because the pressure you start to feel becomes incredible. But one thing it does do is win you every loyalty battle you get into. My ENTP ex (one of the most manipulative people I've ever met, probably) and I had the same group of friends, all of whom took "my side" after the breakup (even more strongly than I was expecting, or even wanted). I didn't even ask. Even the ones that started out as her friend ended up as mine.
The difference between her strategy and mine is that she's much more focused on the short term. She's way better with strangers than I am. And sometimes she's better in relationships for the first month or two. But she always ends up sacrificing long-term for short-term.
Anyways, that's why I'm kinda leaning towards INFJs being more manipulative than ENTPs (it's basically long-run manipulation vs. short-term). Even the INFJs I know that don't consciously think this way still basically use this strategy, although they'd probably argue with me and play defense if I said so. No point in beating around the bush, though.
I can literally say all of this stuff to any of my friends and the strategy still works perfectly. It's pretty much unbeatable in the long-run.
I know you were probably joking when you asked, but I got inspired.