A purification ritual is meant to help people clear their minds and rid themselves of thoughts or emotions that could get in the way of the real purpose of the endeavour ahead. To work magic you need to focus, so if your mind is on other things then your energy will be dispersed. Feelings such as anger, jealousy and hate are particularly destructive. Take time to calm down.
The first purification ritual I learnt was taught to me by Shan Jayran of the now defunct House of the Goddess and the author of Circlework: A DIY Handbook of Practical Ritual. It is simple but effective - my favourite kind of magic.
Take a bowl and fill it with water. Dissolve some salt in the water - traditionally by stirring it widdershins (anti-clockwise) because that direction is associated with banishing or letting things go. Salt and water are used because they are among the oldest cleaning products known to man.
Draw a deep breath, let it out and relax, then speak your worries into the water. If you are on your own, take as long as you need and then a little longer. If you are in a large group think of others who may die of boredom before you finish. Speak out loud if it is practical or just think things through if you prefer. Go into as much detail as you feel is necessary. End by saying out loud:
"May I be free of all doubt and anxiety"When everyone has finished, throw the water away. Do not use it to water plants or make the tea.