I have heard of several ways to do this. The first way I ever heard about is a type of fa-jing shake, where energy is taken out instead of put in. Either way, they end up with more bad energy than good energy. The way which you were probably experimenting with is called astral vampirism, where you mentally draw qi from them. Supposedly, there are 4 levels of this skill, physical contact, close proximity astral penetration (close enough to touch but not touching), line of sight (not close enough to touch but close enough to see), and thought, where you neither have to touch or see them to drain them, but merely think about them.
There is only one way to gather qi and add it to your own supply, and that is to take qi from someplace else. Most of the time, we hear about getting it through the air we breathe. During some exercises we are told to imagine we are breathing through our hands. In any case, this is an introduction to a most interesting subject, but it is usually all anyone ever sees of it.
It is also considered the “dark side” of the arts.
I wouldn’t worry about taking bad qi into yourself. If you keep going, you will eventually learn to distinguish between who you can take from and who you cannot, and eventually you will encounter people you would not dare take from, either because they are vampires themselves (in which case, you couldn’t drain them anyway) or because their qi is so foul they either drain you or make you sick when you try to drain them…or so the story goes.
In any case, I would suggest that you keep such experiments to yourself. People will either think you’re a nut, become afraid of you, or any number of other responses.
And don’t worry about draining people to the point of death or something like that. While I’m sure it’s possible to make people sick doing that, you wouldn’t be able to drain all their energy because when people get low on energy they instinctively and subconciously draw from other people, their environment, etc, to heal the loss.
Don’t think I’m a kook. It’s just that I’ve experimented with this myself.
“I put forth my power and he was broken.
I withdrew my power and he was ground into fine dust.”
-Aleister Crowley, The Vision and the Voice