Lots. The internet is full of them. Most center around making a habit of periodically doing a "reality check" throughout the day, like reading a word from a note and then re-reading it to check whether it changed or not. I carried a note saying "Wake up!" in the pocket and after a few days of maybe a dozen checks a day, the check (like all daily habits) occurred in a dream. The realization when the inevitable discrepancy is discovered is pretty amazing, because it's so completely unexpected and has such deep implications for the experience of the moment. It's definitely worth experimenting with this stuff.
My method was “look at your fingers”. It’s easy, cause they are familiar and often in sight by default. I remember first time raising my hands and seeing that.
I imagine it would be even more shocking when noticed, but possibly easier to go unnoticed - since visually, morphing is continuous in dreams, but word meanings are discrete and can't morph into one another like that.
Btw. funny (and fascinating) how "dream-rendering" has similar issues with producing realistic hands as LLMs. Similar with continuity issues.
It's pretty easy. If you're the type of person who rarely dreams, it takes about a month or so.
First consciously cultivate interest in your own dreams (through dream journaling, and consciously looking forward to your dreams before sleep). That's the basis.
Then, if it doesn't happen spontaneously, to force a breakthrough you can always set multiple alarms (tip: a smart watch with a vibratory alarm, or... make a baby), to wake yourself and keep yourself on the edge of sleep - into that hypnopompic state (between 2-4 AM works best for most people). It takes a lot of effort, concentration & patience. The only thing about this way of entering a lucid dream, is that you're likely to consciously experience sleep paralysis first, and many people don't like that even though it's harmless and a perfect gateway into lucid dreams.
I haven't been into lucid dreaming for a while, but I used to use a technique called SSILD that worked great for me. Search for that name and you'll find discussions about it. You basically cycle between (with your eyes shut) "do I see anything abnormal?", "do I hear anything abnormal?" and "do I feel anything abnormal?" and just keep cycling between those, trying not to actually think about them too hard as you are falling asleep. If you're lucky, you'll end up transitioning into a dream straight from waking consciousness (wake induced lucid dream or WILD technique) or, failing that, you will fall asleep and have a much better chance or realizing you are dreaming (dream induced lucid dream or DILD), and failing that if you wake up in the middle of the night you can stay awake for a short while and then go back to sleep and have a good chance to fall into a dream you can become awake in (wake back to bed or WBTB) and if you do end up having a lucid dream and you wake up if you stay still you might just fall back into it (dream exit induced lucid dream or DEILD).
I had quite a few lucid dreams using this technique, but it has a drawback that you end up having "false awakenings" where you think you just woke up but are actually still dreaming. I've had 7 or 8 of those in a row before. If you have a good reality test (my go-to was holding my nose closed and seeing if breathing lightly would still work) then they are kind of nice because now you have just become lucid again and go do whatever you want.
The whole thing got to be too mentally exhausting for me and I was not feeling refreshed when I woke up so I stopped doing it. I occasionally try to start it up again, but I haven't had the gumption to continue it for very long.
As you can see, there is a huge rabbit hole you can fall down if you look into this stuff, and a lot of places on the internet where people discuss it or give pointers.
Also different people have better luck with different techniques. This one just happened to be my thing, I guess.
