Even a complete beginner can use mediation for stress relief, and with some practice meditation can become an essential tool for completely releasing stress as well.
What exactly is meditation? Depending on who you ask, meditation can be anything from a breathing exercise, visualization exercise, relaxation exercise, emotional introspection, deep thought to even faking meditation by assuming a stereotypical posture (this one is not recommended).
The most basic form of meditation is simply to pay attention to your thoughts. You will notice that thinking is not linear - thoughts are jumping all over the place. Noticing that and 'pruning' unnecessary thoughts is a basic meditation technique. If you combine this kind of calming of the mind with taking deep regular breaths, you got yourself a nice tool for stress relief.
Advanced forms of meditation against stress include visualizing stress (as a way of giving form to your tension and fears), and then imagining a way of releasing it. This kind of visualization exercise establishes a connection between your emotions and your mind, and can show you ways you can use to deal with the stressful situation.