Clearly I'm far less of an expert in these matters than the people who have already posted on this thread (and keep dream journals and/or have lucid dreams on a regular basis), but some years ago I had stumbled on a "lucid dream" forum where people where discussing their experiences, methods to induce lucid dreams, etc. and I was a bit curious so I read upon the suggested methods: the one with the hand wasn't among those, Happy Tree, but there were others* such as training yourself (while you are awake) to regularly pinch your nose shut and try to breath through it. If you do that for some time, make it a habit, you increase the chance that your dreamself will attempt to do it also and they will ... fail, they will feel air pass through the closed nose (because it passes in the real world) and realize this is a dream. So, I actually did that nose-thing for a couple of weeks and it worked, giving me my first (and only) lucid experience, which I kind of "messed" up though. That dream was kind of interesting (I wonder if it was slightly influenced by Dreamfall, also!) and multilayered: I dreamt that in our world a new "travelling technology" was invented, quite similar to Zoe's powers in fact: people could go to special "stores" where they were put to sleep and while sleeping they could project themselves anywhere in the world, so they could visit any place they wanted instantaneously. So I used that in order to meet face-to-face with two very good friends (a boy and a girl) that had left to study abroad (and I missed dearly). Fun fact, because of a picture I had seen shortly before I went to bed I imagined my (blond) female friend as having dyed her hair black, with a bright red streak (like the picture I had seen), lol. So, we met at a cafeteria, chatted (can't remember details), we said goodbye for now and I proceeded to "wake up", only to find myself at my bedroom. I soon realized that I was "supposed" to have woken up at the "dream store", not at my bed, I must be still sleeping! I checked the nose thing and it was confirmed, I could breathe through it, it's a dream, omg! BUT, because I didn't actually realize that the "dream store" thing was also a part of the dream (you could say I was semi-lucid, not fully) I "panicked" that "something went WRONG, I'm stuck in the dream, what if I don't manage to ever wake up?" and that immediately woke me up for good** without actually having a chance to "practise" lucid dreaming, like taking control of the dream. After that experience, I was busy with other stuff so I didn't keep up with the "experiment" and never experienced something like that again.
*other techniques (that I vaguely remember, it's been a lot of years) included turned on and off the light switch (again as a habit), because switches turn to not work very "rationally" (as they are supposed to) in dreams, to look at a screen (like a TV or computer) or a page with something written on it, then look away and the look back to see if the image or text has changed (screens and written stuff turn to be very "unstable" in dreams, they constantly change).
**or am I still dreaming?