I really, really like closing my nose (with fingers) and mouth and trying to breath. It takes so little time, can be done anywhere and without anyone noticing and seems to work extremely easily in dreams for me. Lot of the other recommendations I've read are much harder. (As in flying or putting a hand through a wall were hard to do at first even when I knew I was dreaming. Looking at clock multiple times requires a clock. And all look weird if done in public)

So my technique is find some situation I'm in pretty often in both dreams and in real life, and do this check every time in that situation. After a while it's like a reflex and sometimes I even think I'm surely not dreaming and get surprised.

I've have an amusing anecdote regarding the closing the nose reality check - I once woke up and was feeling strange. Everything around me looked completely real and in full fidelity but I couldn't shake the feeling off so I attempted to close my nose off to breathing and I couldn't breath through my nose as expected.

I still couldn't shake the feeling though and I attempted it twice more before giving up and concluding that I was just groggy and needed to hydrate so got up and went to the kitchen to get some water. Of course, I suddenly wake up with a jolt. The entire scenario was in fact a false awakening and my brain decided to cuck me.

I think for the reality check to really work, you need to not just perform it but really mentally try to will whatever affect you think will break the illusion. The problem with the above scenario is that as I was performing the reality check, I was doing it idly so my brain could easily emulate the expected effect.

the physics in my lucid dreams are generally quite grounded so I only managed to fly after my third lucid dream. Dream control != dream lucidity. They are separate skill sets that you need to train independently.