In ancient literature and historical guidelines written by masters of meditation, students are instructed to assume a comfortable position and then empty the mind of all thought. The purpose behind this instruction is supposedly to clear your mind of any thoughts that might prove to be a distraction.
When people start meditating they are concentrating so furiously on emptying their mind that emptying itself becomes impossible. Just as you imagine yourself sitting beneath a palm tree on the pristine deserted shore, you're might have a thought about how long you should focus on nothing before beginning your meditation...or you'll change your mind and imagine swinging in a hammock in a pine forest instead... reminding you to buy mulch for the front yard...and your mind is anything but empty.
Instead of focusing on emptying your mind, a better approach would be to purposely fill it up with interrelated thoughts that will lead to a clearer focus. For example, focus on a single object, such as a balloon. Then think of everything you can imagine related to it. Balloons are round; they come in all colors and sizes; they start out small and grow larger as they are inflated; they are fragile, they are used in celebrations etc. Extrapolate how all of these characteristics relate to you.
People's faces are often round; they come in different colors and sizes; they begin small and grow larger; they can be fragile emotionally or physically; similar to the characteristics of a balloon. Einstein said that everything in the universe relates to everything else. Thus, you will find that you can relate everything else to a balloon if you focus properly. As your mind slowly fills with these thoughts, it will eventually surrender out of fatigue.
Now that your mind is truly empty, you can fill it back up with the essence of the balloon, which is the essence of everything else in the universe, including you. You do not need to try hard to realize the essence. Reflect on the idea that a balloon is made up of atomic particles and subatomic substances that are no different than the subatomic substances that make up the entire universe, including you. Your mind and body have the same energy and essence as the stars, and all the atomic particles in the universe. Atoms are compelled to merge into molecules, and then those molecules develop into compositions that are increasingly complex. The most complex of all, of course, is the human being, because we alone have the ability to contemplate this miraculous process of evolution and growth, and unite ourselves with the wisdom or consciousness that creates and maintains this essence.
Zen koans (unanswerable questions) have been used for hundreds of years. Examples of these imponderables are questions such as, "Before you were born, what was your face?" and "What is the sound made by one hand clapping?" Another method is to visualize yourself in a conceptual way. For instance, imagine yourself as being the type of person you've always wanted to be, with perfect health, wisdom, peace, self-control, and complete mastery of your body and mind.
Try several different ways to fill your mind in order to empty it, and see which one feels right to you. You may find more than one way that works well.