It is almost impossible to overemphasize the importance of having good backups. There are several methods and strategies available for making good backups. Some are free; some are not. My only absolute rule in a backup system is this: if it's not an automatic system it's hardly worth doing. You may have the best of intentions, but you will inevitably forget to back up files at the worst possible time.
Here are some articles about backup systems. My own personal backup system uses both external hard drives and cloud backups -- belt and suspenders.