I've just been having a discussion with someone who is exhibiting their work for the first time and my first pieces of advice are:
The first reaction people have when they see an image is emotion so I would make sure that all of your selected images are going to evoke a feeling in the viewer.
Secondly, you need to convey your personality in communicating this so it is important that your selected images do not invoke multiple psyches. So, avoid displaying multiple styles. Try and put differing themes on separate walls so that there is a clear distinction where one chapter ends and another begins.
Thirdly, I would select images that the viewer will admire for your photographic skill and creativity i.e. they should not feel "well I could have done that!"