Here is a simple and yet effective way to cleanse the energies within or around you from negative influences/energies. This is useful before rituals (cleansing is synonymous with banishing for some), on a daily basis (you collect negative energies from the people around you as well as any stress you go through, negative thoughts/emotions, or negative spiritual influences, etc.- in that respect think of it like taking a physical bath, only spiritual), or when you have felt a particularly negative influence. Of course, there is also the added appeal in that it typically feels very pleasant.
1. Relax your body, relax your mind, and relax your heart. Be in a comfortable position which will not cause you to fall asleep.
2. Be aware of the space outside of your body. Adjust your consciousness to not only be aware of your flesh, but also the general air and space around you. Keep your awareness generally around, as well as within you when applicable throughout the cleansing.
3. Cause yourself to feel pleasant, content, satisfied, and happy. Other positive feelings are applicable, but make sure that it is a benevolent positive feeling. Let the sensation build for a few moments until you are satisfied in that it has filled you.
4. Direct your focus towards the space above your head, in the air. Concentrate on the positive, pleasant feeling which you have created, and imagine it being there, expect it to be dawn there from the energy currents all around you and above you. Wait as you hold this concentration, giving your intent time to interact with the energy to get it to react to your will.
5. Once you have felt the space above you change the way that it feels, to suit the feeling which you are drawing there in the energy, (or when you are satisfied if you are struggling with this, remember practice and contemplation will help) then visualize a connection through a stream of bright energy (as light or water, or any other cleansing thing you can visualize which you find appropriate) flowing from the point of focus, into your head, and through your body. Continue to concentrate on the pleasant feeling of the energy you wish to draw as you do this.
6. Intend that the energy flowing through you repels/pushes out any negative energy within you. Cycle through multiple 'flushes' using the positive energy, and make sure you are thorough so as to repel any negative energy that tends to stick to you, or that ends up in strange places that you have overlooked (like elbows, etc).
7. Visualize the bright, positive energy that you have drawn flowing around you, scattering and pushing away negatives, including the negatives which you only just removed from within you. This ensures that it doesn't just come back to you, or to someone close to you.
8. Relax, you're done. :)