My understanding is, that almost anyone can send bad energy your way, including a curse or whatnot. It comes down to your own vibration and illusions as to whether the negative energy / entity will stick or not. The higher you come consciously, and the more illusions you surrender, the less effective any negative energy sent your way is going to be at tripping you up.
That being said, I have found personally that the strongest protection against negative energy is forming a relationship with Archangel Michael and calling to him to cut you lose from any and all dark forces and energy that is interfering with you and protect you from any that could. There's nothing more powerful you can do than forming a relationship with this cosmic being who is the protector of humanity (within their own free will).
If you are serious about breaking away from any negative energy that is bothering you, I personally suggest doing this rosary to Archangel Michael a few times (as in a few times over a period of time, like a week, or a month etc.):
http://www.mothermarysgarden.com/J_A...9Michael10.pdf
I found it worked very well for me and the purpose of it is not only to help you and protect your energy field, but also to help the world and allow Archangel Michael to work closer in the world and clear up the baddies who are working against the evolution of mankind.
