Think about ease of installation of artwork you submit for gallery shows...most likely you won't be the one installing it. After all, you don't want your work crashing to the floor because the installation was too difficult for a gallery employee to manage easily.
Pay particular attention to weight/size/display limits outlined in the prospectus. They are there for a reason. If you disregard their stated limits, most likely your artwork won't be allowed into the show.
Make sure all hangers are secure, bases are stable for display, etc. Remember that you won't be there the whole time to watch over your artwork. The general public will be in and out of the space. Even if its a venue with a strict "do not touch" policy, not everyone listens and accidents do happen. You don't want someone to be able to easily knock your painting off the wall or your sculpture off of its stand.
More About Applying to Art Shows