This thread is old as sin, but it surprises me nobody has touched it. For the sake of giving an answer to something still on the front page so that future viewers might see it...
Dreams and daydreams / wandering thoughts are of the same stuff. It's brain activity, and when you approach it from the perspective that both are the same, we can assume that any training of brain activity that enhances focus and concentration will enhance our ability both to control our wandering thoughts and our dreams at night. In many ways, a lucid dream is like meditation. We are resuming conscious control in lieu of the desire to slip off into our dream world, and we're dismissing errant ideas that are not conducive to what we're doing.
How do you increase your frequency of lucid dreams?
Make it your focus to have lucid dreams. Between daydreams and lucid dreams, the factor that affects both more so than others is what your focus is on throughout the day. If that happens to be work, the likelihood that you will have dreams and thoughts concerning practices and/or people at the workplace are increased. Ever had a really awesome video game come out, you played it all day long, and then you had dreams about it? It's because you made that video game a focus throughout your day. So think what will happen if you make it your focus to have lucid dreams, especially for a good twenty, thirty minutes in preparation before bed?
Create visual/mental cues for that focus. Remember the movie Inception? Remember the totems? It's the same concept, though it need not be so complicated. Several times a day, create a conscious habit of checking to see whether or not you're in a dream. Let's say I wanted to make a physical totem my physical cue. Let's say... my watch. Several times a day, I'll check my watch. I'll look at the hands. I'll burn the image of the watch into my mind, so that when I close my eyes, I can visualize it. I can see the ticking movement of the second hand. The slow progression of the minute hand. I'll ask myself each time I do this, "Am I dreaming?" Going to bed at night, I would then use focal meditation on that watch in preparation for a lucid dream, intending both to check that watch, and to check whether or not I'm dreaming.
Suggestion There are many hypnosis files for free on lucid dreaming. Hell. You can pirate a torrent of Steve G. Jobs's files which sell for hundreds, and if you really want the quality stuff, you could pirate a torrent of Robert Bruce's Hemi-Sync. Personally, I enjoy using a freeware binaural beats generator in combination with drone (dull ambient) music, and doing my own self-hypnosis. Whatever you pick, make sure it includes the phrase, "I am lucid dreaming frequently," or some other affirmative present-tense I am phrasing that speaks to you on a personal level.
Recording dreams and thoughts. Be more conscious of your dreams. Train your brain to take note of them, to be aware of them as they occur. Write them down. Not every detail needs to be precise, hell, if I'm really too tired to reach for pen and paper, I just use my phone to text key phrases of the dream to myself and fall back asleep. Similarly, don't let your mind wander willy nilly throughout the day. Take inventory of your thoughts. When you're at work, and you suddenly think of a home activity that would be done at the home, make mental note of it, set the thought aside, and continue concentrating on your work. Build your mental focus, keep your brain on track. When you set out to do something, do it with intent. I.e., when you eat, focus on eating and experiencing the act (eat alone, eat without distraction of any kind), or when you're trying to spend time with your significant other, focus on spending time with that person, don't let yourself get distracted by what's happening on facebook or social media, OR, when you're listening to someone, listen, and don't let your mind wander--small things like this. Focus is a skill, a skill that needs to be built.
How to enhance the quality of your lucid dreams?
One or three pitfalls happen when one begins lucid dreaming; they let their consciousness slip back into a state of unconsciousness after a short period of time, they accidentally wake up, they find themselves unable to affect anything within the dream.
Focal meditation becomes the hero. When one is able to practice being within a deep meditative state, when one is able to visualize and build their world, they become infinitely better at stabilizing their dream worlds and having significant, meaningful experiences with lucid dreaming. I'm not saying that those can't be had without meditation practice, but I am saying that with them, it makes things easier and more natural.
Personally, when I lucid dream, I spend the majority of my time taking note of my environment and doing everything to fill my consciousness with information about the environment. I think about how the ground feels to my feet. I touch things, I explore with all of the sensory mechanics I have available. Sight. Sound. Smell. This helps me retain consciousness and forces an awareness that keeps my mind sharp. If I'm in a specific place that I know is supposed to be representative of a place in real life, I explore it. If I'm in the bedroom of my childhood, where I often automatically go when I realize I am conscious, I try to pick out the discrepancies of how it is within the dream to how I actually kept it. If I am in my own bedroom, I try to take inventory and to see if everything is there. To see if I can find my cat.
The above are astral projection techniques, but astral projection and lucid dreaming are, IMO, largely connected.