I have wasted countless gallon ziplock bags when traveling - just unscrew the lids and put some plastic wrap over the opening then screw the lid back on for a much easier spill solution! (not quite as safe as a plastic bag, but a good idea!
Never lose a button. Buttons are a great way to keep earrings organized. Insert the pair into a button and keep them together to prevent loss. This is one of my favorite tips for traveling with jewelry!