First off, I feel it important to point out that my own views on negative psychic energy have shifted markedly as a result of my own spiritual journey. Having been taught from an evangelical Christian perspective from my earliest years, I now joke that we usually heard more in church about "the devil", "demons" and the "Antichrist" than we ever really learned about God.
This is not to say that I am "anti-church" or even "anti-Christianity." Rather, the opposite is true: all of the major world religions - Christianity, Islam, Judaism, Wicca, Zoroastrianism, Buddhism - all of them offer something of value. However, the issue of religious dogma can be problematic - when religious institutions basically make the claim, "our way or the highway." In fact, there exists much overlap between the major religions. All advocate that we pursue spiritual truth, behave ethically toward others, and do not cause harm to ourselves.
Many of the religions teach, though, that God/Creator is some force external unto ourselves. Likewise, we learn that some contradictory, negative personified force exists to sabotage our every endeavor. Many people fear the work of psychics, spirit mediums, witches and others because they have grown up amidst this misinformation. Truthfully, I have never happened upon a spirit I would consider "evil" in my work as a medium and psychic, but I have had to clear negative psychic energy from the physical environment and often teach others how to do the same - without the frightening advice frequently imparted by unscrupulous, self-proclaimed psychics, who too often are all too eager to sell an unnecessary "curse removal" service or product. Messages I have received from clients' deceased loved ones, pets and angels have always been encouraging, loving and supportive - a far cry from "evil."
So what exactly do I mean by "evil" and "negative psychic energy"? Quite simply, we are not limited to our physical bodies, and our physical bodies do exact an effect upon the environment around us. One example of this might be an occasion when we have walked into a crowded room. We can sometimes instantly get a feel for the energy within the room - even before anyone speaks to us. We can tell intuitively whether the room is a place where we really want to be. The same thing occurs in our homes and places of work: stress, depression, anger - all of these have a direct and lasting impact upon our physical spaces. Even our unconscious feelings can affect the environment around us, so spiritually caring for ourselves is just as vital as physical exercise, diet and good mental health.
Pay attention to those subtle feelings, though. Trust in your own personal ability to project positivity and to exude love for yourself and those you meet. Most of all, take a few moments each day to bring to mind those things, for which you feel most grateful. You'll find that you feel much more content, less fearful and ultimately empowered in your search for Truth.