Simply, when you sit down make sure you're comfortable. You can meditate anywhere, but if you are at home, loose clothes is ideal. Whatever your driving factor is that's making you meditate; try your hardest to forget it for the time being. Sit with relaxed but healthy posture, and make sure to breathe deep consistant breaths. Laying down is always great for meditation, but to stay in the most coherent state of mind sit up and close your eyes. The key component to this is letting all thoughts run through your mind like water; the thought of an empty mind even, should not exist. Thinking about absolutely nothing is tough, this will likely be the most challenging part, but stay consistent in your efforts, you'll realise time moves slower in this state. Once you've achieved this state of mind, you are clear to start working on changing what it is you want to change about or in your life.