How to give a good 2 weeks notice?

I need to give my notice to my current employer. The work is horribly boring and one day my boss is the nicest guy ever and the next he is not. I am going to give my verbal and written notice tomorrow. How should I handle that- give them both at the same time? What should I say if he asks why I am leaving? I am taking a $6K pay cut for the new job!