Know your business requirements: How long a company need to keep its backups is based on legal and operational requirements for each type of system. Keeping the backups for longer than required will unnecessarily increase storage costs.
Keep IT simple: The most reliable backup systems are the simple ones. Over complicating your backup routine, makes the backup system harder to maintain reliably.
Make sure you understand your RTO and RPO needs: Understanding these requirements is important to ensure the backup system meets the needs of the business.The Recovery Point Objective (RPO) describes the point in time to which the data must be restored.The Recovery Time Objective (RTO) is the measure of time and service level within which a business must be operational to avoid unacceptable consequences associated with a loss of IT systems.
Know what needs to be backed up: Lots of storage and network bandwidth is wasted from backing up data that is not required. Also poorly configured or managed backup procedures may not be capturing all of the key system or important files may inadvertently be excluded from your backup routine.
Backup systems are not an archive: Keeping backups for archiving purposes is not what backup systems are designed for. Well run backup systems are designed to recover the data in the event of a disaster so that no data loss occurs. They are not designed to become an archive of old data to reduce storage usage on production systems; that is the role of a dedicated Archive system.
Embrace multiple forms of backup media: Do not rely solely on one type of backup media, use a combination of different types. This could be External hard drives, USB sticks, Online backups to the cloud, NAS (network attached storage) etc. In other words do not put all your eggs in one basket.
Tape is not dead: Despite the advancements in other backup media, its hard to beat tape on cost and speeds. Tape is still a good choice for long term backup retention.
Have a Disaster Recovery Plan; Failure or an IT system is the last thing you want to happen, but when it does do you know how to recover your critical system and restore the data? Therefore create a disaster recovery plan and regularly test it works to be sure you can recover your data in the worst case scenario.
Test it works: You cannot rely on a system you have not tested, so carry out regular restore tests to be confident you can recover your data.
Be realistic; In an ideal world it would be nice to have multiple backups of every system, every day, stored in multiple offsite locations. With the ability to carry out a full restore within an hour but its unlikely to be possible. So be realistic about how often you backup each system and that the targets you set are achievable to recover your systems and data.