I have had lucid dreams for as long as I can remember, and I have never used any techniques.

How it happens is related to my thought process and brain, normally when I encounter something that I have not before I think it through rather than acting on instinct, and I try to recall past situations that may have been similar. this is what I do in reality, and as a result it is what I do in dreams. however it by itself is not enough to cause a lucid dream, no, what does it is that when I try to remember I feel this... fuzziness in the back of my head, like I am missing a large portion of my brain that I would normally be using to analyze the situation and access memories related to it. The closest analogue I can think of is the effects of Marijuana, (Or six-hour allergy pills) like all of your higher brain functions are being suppressed.

Then to confirm that I am actually dreaming I simply force my thought process (which is... hard to describe. but basically involves thinking through how the world should be and how it is different now) if the world changes to fit what I think it should be then I am dreaming. if it doesn't change then I keep trying to figure out why it would be that way until it does.

I know the above sounds a lot like a technique when I present it that way, but it's really not. it is a natural extension of my thought process, and has been occurring almost every night since I was a child. (long before I even knew what lucid dreaming was).