Have no hanging requirements since they are not subject to the elements.
Exterior against a solid surface such as a building.
Try and minimize the banner flapping by using screws and washers at every grommet. Rope applications can be used but the goal is to keep the banner as flat to the wall as possible. The flapping of the banner can quickly ruin the vinyl and print so if it does come undone you need to secure it as quickly as possible.
Exterior free standing banner application.
Try and minimize the banner from flapping at all times. Be aware that your banner acts like a sail and it needs to be able to spill the wind to survive in this type of installation. Best application practice is to hang the banner from aircraft wire on the top and bottom and then secure the side grommets to the side support with bungee type cords. All grommets should be used and attached to the wire in a manner that allows the banner to slide along the wire. Carabiners (climber's hooks) are great and can be purchased at your local hardware depot.