For safety, you can follow the instructions on the canning jars for sterilizing them first. It should list how long to boil them. Rather than boil mine, I usually put them in a dishwasher and run through a full wash-rinse-dry with soap in the wash cycle, to clean and sanitize them before using. You can fill them hot from the dish washer, or keep them hot in the oven at 200 degrees. Be sure to soap and water and rinse the lids before heating them in the pan on the stove. Jars can be reused until they chip or crack. Better not to reuse flat caps. They don't seal as reliably after the first time. Take the ring off after the jar is completely cool so it won't rust from water inside the threads. The rubber inside the lid and the vacuum will hold the flat cap on. Check each cooled bottle to be sure the lid is popped down and won't move when pressed in the center. You can put a flat cap on an empty jar to see how they sound and feel when not sealed.
This is basic info that anyone who canns at home knows, but almost no one makes their own pickles or jelly these days, so I thought the specifics might be helpful.