What is a WILD?
WILD stands for Waking-Induced-Lucid-Dreams. All this means is that you enter more-or-less directly from the waking state into the dream state without a lag in conscious awareness. Usually, we do not enter directly into REM-sleep and dreaming directly from waking because the typical cycle goes from Waking to Stage-1, then Stage-2, -3, -4 Sleep, then into REM-Sleep, then a brief awakening, and the cycling repeats five or so times each night. Earlier in the sleep cycle, there is more Non-REM Sleep per cycle, and as we approach morning awakening, the tide shifts and each cycle becomes increasingly dominated by REM-Sleep and longer dreams. The cycles are about 90-minutes long, and the last one may consist of dreaming which lasts for about 45-minutes.
Because there is less lag naturally between the beginning of the last cycle and entering into dream-sleep, this is the optimal time to attempt a WILD. Also, if your sleep schedule has been disrupted - such as if you are sleep deprived - the order of things may be different and occasionally we enter REM as soon as we go to sleep, but this is not very predictable.
Most people find that using the Wake-Back-To-Bed (WBTB) method enhances the possibility of WILDing. The trick is to fall back to sleep after fully waking up (an hour or two before you would naturally wake up for the morning) while maintaining awareness of your intent lucid dream. If you have practiced seated meditation, you may have noticed that the mind, when not occupied by external stimuli, tends to drift off into imaginings and it easy to forget that these mental images are not really happening in the outside world. There is an aspect to the mind which has been labeled the "Observer," and this is the part of you which watches what is going on, not the reactive part of you that moves muscles. The Observer part fo the mind can be strengthened through meditative exercise. When the mind begins to wander, we gently try to maintain in the seat of the observer. Do not let yourself get washed away in your mental imagery, just calmly watch what is happening. Do not try to push the thoughts which spontaneously arise down, just watch. This is difficult while awake, and even more-so when falling asleep. Know that you do have the ability to maintain awareness without being swept away into the arising illusions. This critical type of observational consciousness can be heightened through supplements, but too much cerebral activation in this direction would make it very difficult to fall asleep. Balance is needed.
The best description I have ever heard of for learning how to WILD came from the brilliant physicist Richard Feynman in his book "Surely. You're Joking, Mr. Feynman!":