Spirit guides and contact?

I was reading online about spirit guides. My family is very spiritual, and I know I have gained some senses. I feel awkward asking family questions, but I really wanted to know about spirit guides and i wanted to know if my father whom ped away 3 years ago is around me and protects me. I feel him often. The main thing I am worried about, is on every website describing spirit guides and methods of contact there is warnings. These warnings describe a spirit that pretends to be your guide but isnt. That worries me, I do want to find out if I have a spirit guide, and i want to communicate with that guide but the warnings I read deter me from wanting to. What are the dangers, why would a spirit want to cause harm to me? I am not one who goes looking for trouble therefore I would believe I would not be bothered. When I am afraid, as my mother has taught me, I say "if you are not here to help me then go away" that usually works. Also, when thinking about spirit guides I often get a warm unusual tingling in my right arm, what is this? it is more like a muscle feeling. I know it is not my dad because he offers me scents and touches my left hand. Also, when i feel I am ready to see my dad, at random moments when I am not expecting it I will see a mist quickly appear and I feel it is him, then as I think oh no i'm scared, it disappears. then i apologize in my thoughts and tell him i'm sorry i am not ready, but thank you. And advice would be greatly appreciated.