M31 is easy to find and image, but hard to image well. That is, it requires making a mosaic of at least two different images to show both the brighter core parts and the dimmer outer regions well, since our cameras lack the dynamic range to handle both equally well in a single exposure.
It is also very large in apparent angular diameter, so you need a widefield optical system to see it. It's best in binoculars. Widefield telescopes like an 80mm or 90mm F6 scope will show it fairly well.
The reason most people are disappointed in the view at first is that they have a longer focal ratio telescope and/or use too much magnification. In a typical 8" or 10" newtonian of F5 to F6 ratio, you need a very wide-angle eyepiece of less than 40X to see that it is a galaxy and not a fuzzy-looking globular cluster.
At this time of year in the Northern Hemisphere, wait until about 3:30 a.m. for it to rise high enough to see well. It rises in the NE. A more convenient time of year for observing it is August or September, when it is high in the sky just after dark.
Look for it between the W of Cassiopeia and the Great Square of Pegasus. This time of year in the early morning hours, follow the top part of Cassiopeia's W going South, parallel to the horizon to the northeasternmost part of the Great Square of Pegasus. You'll find M31 is a fuzzy patch about 2/3rds of the way from Cassiopeia to that corner of Pegasus and slightly above the line that joins the "point" of the W to that corner.
Here's a good online article about finding and observing M31.