I also don't have solid dream signs. There are some, but I don't see those in waking live often / at all.

For me, just knowing that clocks and light switches behave odd in dreams caused me to get two lucids. I suspect I was basically on the verge of lucidity before - both LDs were DILD, but from a botched WILD attempt - I assume that I already had an idea I was dreaming before flipping the light switch / looking at the clock thrice. I did not really train to do those reality checks, I just noticed the presence of a light switch, flipped it and since it was not working I became lucid.

If I do see a digital clock in waking life I now look at it twice to ingrain a habit, but thats it.