At night when it's quiet. Lay on your back with your eyes open. Don't move your body at all and your brain thinks your body is asleep and will try to move it but when it decides it's asleep you will start to have weird hallucinations, hear weird noises, see people who aren't there and stuff.
I want to try it but I'm scared D:
It isn't scary. I have done this many times, it is quite simple actually. Pretty much what you said.
Lie down on your bed, with your whole body in a "plank" position. You can turn your head to the side so it lies on your pillow the way you like for comfort. Eventually, you will feel a small tingling feeling at your toes, at this point make sure NOT to get excited or it will go away. Just keep lying there, and wait, it will come soon. You will feel your whole body slowly (from your toes up becoming numb. This experience actually feels kind of good in my opinion. Do NOT worry, you will most likely not hallucinate, this only happens on some occasions. Now just lie down in that same position, until you fully fall asleep, at that point, you should be able to lucid dream.
(NOTE: That if you feel that you will be scared, tilt your head to the side, so that one ear is facing up, and the other is on the pillow. Then place your blanket over the exposed ear. If you are still scared, place the covers almost all covering your face, and leave a hole for breathing. This will make you're fear fade away.)
I have done this plenty of times, although, you will most likely end up in sleep paralysis the first time or so (make sure to note that sleep paralysis is NOT ALWAYS SCARY, just enjoy the experience.)
When I have done this, I have many times been stuck in sleep paralysis, but sometimes I do end up LDing. And when that happens it is AMAZING. (Although a lot of the time, I just end up doing something relating to research..
and ending up having a wet dream...Anyway, just follow this! :)
And remember it is really not that scary!