The following probably won't flow together as a story too well, so forgive me - They're all separate incidences that occurred at different times throughout our twelve or so years that we have lived here.
I'll start from the beginning.

My father (who is a very skilled metal worker and handyman) bought our house as a ramshackle, run down mess with plans to renovate it into a comfortable place to live. A few of his friends, who share the same talents, helped out with this project on a regular basis.

Every night after work, he'd go and chip away at the work of renovating our new place, and most days one of his friends would knock on the door, offering a helping hand. On numerous occasions, he'd hear footsteps on the front porch, and the familiar knocking sound on the door - Only to find upon opening the door that no one was there.
After our family moved in, we all became aware of a presence in our home. There are so many instances of strange things occurring to each of us, that i'll only go into the strangest ones of all, so as not to ramble on.

We'd all go to bed at night, usually at different times and whilst lying there trying to fall asleep, we'd feel as though someone was watching us. This would be followed by the sensation of ice cold air upon our faces, which felt like someone breathing on us. If you asked it to stop, it would cease. I was the first to actually see the spirit in our home, but since then my mother and sister have seen it also. Even friends who have stayed overnight have seen it, or heard it rustling about the house. It looks like a haze of smoke, and very nondescript. On two separate occasions either the oven or the kettle have been turned on, not by anyone in my family who was in the house at the time, and things have been known to move around on their own - eg. something placed securely on the middle of the kitchen bench will suddenly fall off. Things often go missing around the house, and after a mad search to find them has taken place to no avail, they'll show up either in the place you swear you last saw them, or somewhere totally unexpected and nonsensical.

Once I tried printing out a ouija board I found on the internet to try and communicate with our spirit. I left the computer to have a cigarette as it printed, only to return five minutes later to find the internet had disconnected, but the computer was still on. I tried again, but this time asked our spirit to give me a sign if I was doing something it didn't like. Nothing happened, so I continued. Very shortly afterward, my dad's alarm clock in the bedroom went off (weird because it is set for around 6:30 am, and the actual time was around 2:30 pm) and all the clocks in the house that were electric - eg.the clocks on the video and microwave - were displaying completely different times, ruling out a power failure or blackout of any sort.

Once my sister heard my dad's name being called out down our driveway as though a friend had arrived and was checking to see if he was working in the shed, but when she investigated outside, there was no one there. My dad was actually in the shed at the time, but when my sister asked him later that night if anyone came to see him or if he heard what she heard, he said no. My sister and I are the only ones out of our family who still live at this house, and we have eight cats. Very often we'll see them staring at things that aren't there, with the fur on their backs standing on end and wide, alarmed eyes. I have heard that children and animals can perceive these things better than many adults can, because they have no pre-conceived ideas or beliefs on the subject.

One time just recently, I saw one of my cats in this state standing in the kitchen, looking very startled. When I approached him to give him a reassuring pat, he ran away frightened. I moved into the spot where he was looking, and felt a feeling of terrible dread come over me, which was very uncomfortable. I had to leave the house, because I didn't recognise this feeling associated with the spirit who was there, as I normally do with the common spirit or spirits who visit my home. There are many more strange things that have happened to my family and I, but i'll post these separately.

Thank you for the opportunity to explain these incidences, without being looked at as if i'm crazy!!!