If you want a minimal effort technique, you can try hypnosis. Instant Self-Hypnosis by Forbes Blair is a great choice. It clears up all the misconceptions about hypnosis in very straight-forward manner, and offers a script for lucid dreaming. You only have to read it once a day (takes roughly 15 minutes a session) until you start seeing results.

Or you can watch a hypnosis video before bed. Preferably one that's 30 minutes at the most.  

It's still a work in progress, but I did manage to attain lucidity once during a nightmare. I could hear the words from my hypnosis script verbatim, allowing me to regain some control and essentially destroy the nightmare figure (with a katana I summoned out of thin air, surprisingly lol).

I originally used the book Instant Self Hypnosis, the first edition. But you can watch youtube videos prior to sleep, preferably 30 minutes at the most.