Welcome to the forums. Keeping a dream journal will be important. Just pick the way that works best for you and stick with it. There is no research behind bananas or apple juice inducing lucid dreams. So there isn't really a point in consuming them just to lucid dream. When it comes to mantras, pick one that you will want to use. And you need to choose a mantra for your specific application. For example, "I know the feeling of dreams" has worked well for me when I MILD. You can create your own or I will suggest some based on what you want to use the mantra for.
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