There are two ways Ive heard are really good. The one that I tried and had success with was every time I walked through a door was touching the frame and asking myself “Am I dreaming?” and really think about it. The answer will obviously be no. But then you get into such a pattern of doing this that you start doing it in dreams. And soon youll see your answering yes, yes I am dreaming. And the lucidity begins.
Adversely you can write a letter or something on your hand and every time you notice it, ask yourself that same question above.
The hardest part IMO is when you finally start lucid dreaming the first couple times, not getting too exicted. Like I would be like YES HOLY SHIT IM DREAMIN RIGHT NOW!! and that would wake me up lol