There are probably as many ways to shed negativity as there are Witches who need to do it. Some of them may be quite complex. Some of them are very simple.
One method I have used is a purification bath or shower. For the bath I add a handful of sea salt to the bathwater, and perhaps a few drops of sandalwood oil. As I soak in the bath I feel my cares and burdens wash away, running eventually down the drain and far away from me.
Even simpler is just to stand under the shower, close my eyes, and let the water wash away all of the negativity around me as it flows over me. (Remember that running water is a powerful cleansing tool of itself.) The water and the negativity eventually run down the drain and return to the Earth where it is purified.
Another method I have used is to pick up a pebble from the ground. As I hold it in my hands I visualize all the negativity inside of me as a dark mass. Then I use my own energies to "push" the negativity down through my arms and hands and into the pebble. When I feel that I have removed the negativity from myself and placed it in the pebble, I toss the rock over my shoulder and walk away...even better if you can drop the pebble into running water such as a stream or river.
Another useful exercise is to set aside time every day for a small ritual. Light a stick of incense to place on your altar and thank the Gods for five good things that happened to you that day. They don't have to be big or important things. It might be something such as thanking them for seeing a beautiful sunrise. The idea is that this reminds you that there is something good which happens to you every single day.
There are numerous meditations that one can find to help deal with negativity. One that I particularly like comes from the book "Mother Wit" by Diane Marie Child.
Shedding The Cloak of Negativity:
Relax, deepen and protect yourself. Here in this space out of time you are becoming conscious of the garment you are wearing, a cloak, a heavy black cloak. The dark, hooded robe is the cloak of your negativity. It symbolized all the negative thoughts, feelings, and experiences you carry with you. Feel the heaviness of it. Become aware of the texture and the feel of the cloth. Feel the weight on your shoulders, your whole body cloaked in negativity and despair. (Pause about one minute)
And now become aware that the cloak is gradually lifting up and away from your body and with it your negativity and despair. Now the cloak has vanished.
And your attention isw drawn to a fountain, a foutain of light, an incredible fountain of light. And the shimmering light is bubbling up and spilling over. A shower of light, a shower of stars, thousands of tiny stars, is streaming down upon you. The whole space is filled with a brilliant glow.
And you realize that you are gowned in a new garment, a sheer translucent cloak of light woven from the stars. And you are wearing this robe of love, joy, and protection. Wear it now and always. When you are ready, drift up and back to your waking reality filled with light and love.
Now getting rid of negativity once is great..but it tends to come back again. We pick it up at work or at school and we track it into our homes like mud on our feet. So it is a good idea to be aware of the negativity we are bringing hone with us and get rid of it before we come into our home.
I used to have a very stressful job that was causing me problems because I would bring it home with me every night. I decided that it would be a good idea to leave all that stress at work. So at the end of my day I would visualize all that stress and negativity sitting on my shoulders, and I would physically lift it up and place it on my desk, telling it that it needed to stay there and I would come back the next day for it.
Another way of leaving the stress and negativity outside of your home is to use the pebble exercise I mentioned earlier. Or to simply lay your hands on some object outside your home and push the negativity into it. (Warning, don't do this to a living object such as a tree or shrub..the negativity can kill them.)
And since over time some negativity WILL manage to get into your home, I recommend a periodic cleansing of your home. Smudging with a sage wand is a good way of doing this (But do be aware that the smell of burning sage can be mistaken for the smell of marijuana and neighbors might talk!). Personally I like to use a cleansing solution of water, sea salt, and a bit of lemon juice. It smells fresh and clean and does a good purification job. You can also burn a black candle, seeing the negativity absorbed as the candle is consumed.
These are but a few ways to rid yourself of negativity. I would also suggest combining these ideas with my affirmation exercise since negativity is basically a faulty way of thinking about ourselves.