Just keep it in an easily accessible place. Get familiar with it and its operation. Make sure you are comfortable with retrieving it from said location. For example, I keep a small .380 in the left hand drawer of the desk I am typing on right now.
I have a Mossberg downstairs in the closet by the television. I have a Marlin 795 in the closet of the upstairs bedroom. I have a .22 in a kitchen drawer. I don't have anyone else living with me at the moment, so it's not necessary to have a gun safe at this point. Instead, I keep each one of my firearms in a location central to where I would most likely be in the house at any given time. That way, should the need arise (and, it never has and I hope it never will) I will have immediate access to a weapon and be able to defend myself.