Find the constellation Cassiopeia, which has a distinctive "W" shape (although its orientation changes at different times of year as it circles the north celestial pole). On fall evenings, look for Cassiopeia in the northeast, where its tilt makes it look like a "3", and in the winter look high in the north above Polaris, where it is oriented like an "M".
Once you have located Cassiopeia, look at the two stars that form the last line of the W shape (Caph and Schedar). Use these two stars to form a right triangle extending outside the W shape, as shown below. NGC 7789 will be at the third point of this triangle, and it should be easy to see in binoculars or a finderscope.
