Without calm stability you will lose your presence and lucidity in a dream. Your mind will start to wander and stars to grasp or resist thoughts and emotions that rise in your mind automatically. The dream will carry you away unconsciously. To prevent this you need to learn to rest in one pointed mind for at least a couple of minutes or preferably more.
Meditation is traditionally used to develop one pointedness and stability of the mind. The object of the meditation can be anything. It can be a sacred image inside your mind or it can be some words or mantra or a single syllable imagined or said inside your mind, it can be a color or a point of presence inside of your body. Breathing is a natural choice for effortless focus since you always have it with you and it is something concrete to concentrate on. Pick you favorite and do it regularly.
In fact the only thing you really need to do for a lucid dream is to learn to rest in your presence and without losing yourself inside your stream of thoughts and emotions. They are fine in themselves but they make you to lose your inner balance creating conflict inside you that will affect other people around you. The process of meditation and being and staying present in what is happening is the same thing that happens in a lucid dream when you become conscious and present and know where you actually are. So meditation is a lucid dream practice as such.
The trick of resting in peace of mind or meditation is to make it fun or to have a deeper purpose in your life. You can become inner buddha at least temporarily and shine peace and joy of being for others. You can continue your life as it is but you will be creating more peace and joy whatever you do. So pick a meditation object that you enjoy staying with. This way you will practice more and maintain your motivation. Do it every night before you go to bed and it will change your dreams. Learn to value your own peace and joy of being as you were meeting a buddha or a sacred person. It will transform your life and the life of those close to you when you become little by little a much nicer, warmhearted and friendlier person towards others.
When you learn to meditate and concentrate on an object for some minutes you can try meditation without an object. This is just resting in pure presence without a particular focus outside or inside. In fact you always have this pure presence with you. Your own consciousness is already it. Sometimes it is called Nature of Mind or True Self. It has fancy names like enlightenment, mystical union and so on but you don’t have to search it from very far because you already are it. A buddha or awakened one is a person who can rest in this pure presence continuously without losing the stability in thoughts and emotions of internal or outside world day and night. Anybody can learn to do this at least for a little while. With practice you will come better in it until it becomes a natural state for you.
When you learn to fall asleep in state if one pointed focus or presence you are very close to lucidity in your dreams.