When checking for doneness, bend the jerky to expose the muscle fibers. If you see hues of red/pink, the meat is visibly moist, or it's rubbery, it needs to dehydrate longer.
If the bend is dry and has white spider-webbing, it's considered done.
As the jerky finishes, put into a sandwich baggy with the top open. This way you prevent condensation from happening inside the bag and you allow heat/moisture to escape. Once it's cool, close the bag and store in a cool/dry/dark place.
For longer storage, use a freezer bag/vacuum sealer with food-grade desiccant bags.