Deep meditation is a little different than meditation. Going deep means your mind is going from surface awareness to subtle awareness, and ultimately to no awareness. To do deep meditation first you have to know what your mind is, what you are. Deep meditation means complete control of your mind. To control your mind first you should know what your mind is because you cannot control what you don't know. When you try first it will be hard for you but then after practicing for some time it will be easier and you will be used to it. As your mind travels through the various degrees of awareness, you'll be thinking various thoughts, many of which won't have anything to do with meditation. Sometimes in deep meditation, we can go into the parallel world or imaginary world created by us. It needs a lot of time, practice, and experience to do deep meditation.