How can I keep my tools from vibrating?
Random orbital sanders are designed to be used with specific sized pads, with a precise weight. Make sure you are using the correct size pad, and that it is in good condition.
Changing your backing pad when necessary will keep the vibrations of your sander to the minimum. Large chunks of missing pad material will cause imbalance.
If you are using a pad saver, make sure to counter balance it correctly.