Choose a quiet place. You can cross your legs (like a traditional Buddha) or sit in a chair. The key is to keep your back straight to stop your mind from becoming sleepy.
Allow your eyes to close naturally and focus on your breathing, without actually trying to control it. Breathe in and out through the nostrils and become aware of how the air feels as it enters and leaves your body.
At first, your mind will be full of jumbled thoughts and it may feel like things are getting busier. In fact, you are increasing your self awareness and noticing how many thoughts you really have. Avoid the temptation of following your thoughts as they occur. Stay focused on your breath going in and out of your nose.
If you realize your mind has wandered, bring it back. If you keep this up for 10-15 minutes, you will achieve a quiet state of mind. Your thoughts will be clear and lucid, like a calm lake that has not been disturbed for a long time.