For clearing the mind, zazen(zen meditation) can be one of the most effective ones. The only thing that is really necessary is a comfortable place to sit(optional: cushion and sitting position such as the lotus, burmese ect.), straight back and zero distractions. Take about 5 deep breaths to get your body into a state of relaxation and start to breath from your nose only in a rhythmic pace(after time, this will happen naturally and you don't need to focus on it).
The key is to let go. Basically, try not to change, or resist any thought that comes to your mind. Obviously, thoughts will come to mind. Instead of trying to push them away, or change them, do nothing. Embrace them and accept them.
See yourself as if you're sitting in a theater. Your mind is the movie and you're the observer watching it. Doing this long enough, you'll start to notice that your thoughts will begin to silence themselves and sooner than you know you will be literally in a state of 'nothingness'. What most people want to achieve with meditation to 'clear the mind'. The key is doing absolutely nothing about your thoughts and practice meditation each and every day for at least five minutes(if you want to get serious about it and see the permanent changes it can have on your life). See it as a necessity. Like brushing your teeth.