A technique I like to use when I've not been doing any lucid dreaming for a while is something I call lucid dreaming during the day. Basically, after I've done a reality check and found that I'm not actually in a dream, I will PRETEND that I am in one.

I will act as if the reality check failed and I realized I was dreaming. Of course, I don't fly out windows or do anything that might have dire social consequences. I just say to myself, "okay, this is a dream, try to focus on the details of it so you will remember when you wake up what you saw and heard,etc." I try to drag it out for several minutes continuously.

I try to pay particular attention to sensory details all the while telling myself that all of this is being "created" by my imagination. That includes sights, sounds, tactile impressions (like what does it feel like if I touch something cold, for example). I will perform some experiments like I'm a researcher studying the dream world (even though I am awake and in the real world).

I find I usually start having lucid dreams again within a couple of days of doing that. What it does for me, I think, is get me into the mindset of just being aware. For me, lucidity is just awareness. I can use this technique while driving, watching a movie, talking to someone, whatever. It's just practicing awareness and pretending you are aware that you're dreaming.

That mindset of awareness -- if I practice during the day -- will carry over into my dreams and I am more likely to notice truly "dreamlike" things that happen. Most of my lucid dreams do not come from noticing my specific dreamsigns, but from becoming aware almost naturally that I could be dreaming and then realizing that I am.