How Do You Choose Which Artworks To Exhibit At A Gallery?

if you having problem of choosing which to show, you should ask the gallery's help. Usually the gallery have a theme or idea for each shows.

Agree with Alfred.
If you were selected by the gallery which piece or pieces were they most attracted to? Which image interested them to want to show your work? Do they have a theme in mind, does the venue tend to exhibit particular subjects/styles? Is there a price point based on what they usually sell?
If you know that then you have a starting point and can add pieces based on what they were attracted to initially. If you are still in doubt it may be a good idea to also ask your collectors/ and regular customers what they would like to see in an exhibit of your work. A balance of that in terms of input in addition to what you would like others to see of your work.

Thank you, Chaline and Alfred! I find your advise very useful! :-)

It's your art, choose what represents you. Do you want to put your art for sale or do you want to sell stuff?

Randi,
The gallery chose you so let them guide you.....also ask how many pieces they have in mind.
I always go for a cohesive look...there is something to be said for people recognizing a style and remembering the artist.
Congratulations and take pix to post here if you can!