What Are DILD's
Dream Induced Lucid Dreams, or DILD's, are lucid dreams which are initiated after the dreamer is already in a regular dream. This is as opposed to a Waking Induced Lucid Dream (WILD), which occurs with no loss in consciousness between waking-falling asleep/dreaming.
DILD's are likely more common than WILD's, because it is very tricky to maintain consciousness as you fall asleep; in fact, many claimed WILD's are probably DILD's, except the gap in consciousness between waking and dreaming is so brief (several minutes or less) that it feels like there was none or almost no gap.
Although it is a good exercise in conscious-persistence to attempt WILD's, the ability to achieve lucidity in a dream from inside of the dream, as in DILD's, is an easier affair, and this is because we can train ourselves to become aware of dream-signs. Dream-signs are items or events/themes which we can recognize as being typical of our own dreams. This is facilitated by keeping a dream journal, studying it, and becoming increasingly aware of what to expect in your own dreams. This is easier than t may first appear because there are only a dozen or so common dream themes which all people have throughout their lives. Further, themes and content in dreams is often grouped into similar occurrences over short periods of times - if a situation at work or school or home-life is to trigger a particular type of dream, this dream will recur while the waking event is still fresh in memory. You may notice that over the past week you have had recurring chasing dreams. What to do? Keep repeating to yourself "The next time I am being chased and cannot get away from (insert here your bogey-man) I am probably in a dream!" Eventually, you will realize this in a dream, and continue on by 1. Reality testing (using the read text-look away-look back method, or try poking your finger through your hand), 2. Stabilization technique (spinning or rubbing hands together or saying "Increase Lucidity Now!"), and 3. Pursue your pre-planned lucid dream goal (whether it's flying or telekinesis or visiting the deceased, etc.).