For most cases, non-sterile is sufficient. You can buy them in a pharmacy, medical supply store, and from vet supply catalogs. Wash your hands, dry them, then put the gloves on. With non-sterile, just put them on and do what you need to do. Laying things out before you put on the gloves is a good idea.
Sterile saline is just plain contact lens solution.
That is, you can buy sterile saline from a vet supply company, but the contact lens solution from the pharmacy will also work. Make sure that it is plain . Avoid the ones that have protein removal stuff in it, for instance. Sterile saline is used to wash out eyes or small cuts. Just keep in mind that once you touch the tip of the bottle to a surface, it is contaminated.