I'd say the DILD method is the safest route, for credibility's sake. At the very least, I suggest you only include techniques you personally have used. Be sure to include dream recall and WBTB technique, along with dream journals and junk like that. I wouldn't go into specific sensations, since these are impossible to professionally describe, and are different for everyone. The basics are sure to fill whatever time requirement there is. I'd not forget to explore all of the applications lucid dreaming has (changing nightmares, adventures, overcoming certain phobias like public speaking, heh, heh). If you still have time, you could talk about sleep studies.

Find sources *cough*ETWLD*cough*Dreamviews*cough*. Cite them in your speech. If your teacher doesn't require you to site your sources, you have a very lax teacher, and I suggest to cite your sources anyway. Including quotes within your speech boosts credibility immensely.