It's easy to put off backups when a site is small - "it's not that important yet" - right up until something happens and it very much was. A few basics worth setting up early:
- Automate it. A backup that depends on you remembering to run it manually will eventually get skipped at the worst time.
- Store copies off-server. A backup sitting on the same machine as the site doesn't help if that machine has a hardware failure or gets compromised.
- Keep more than one recent version, not just the latest - sometimes a problem isn't noticed until a few days after it happened.
- Actually test a restore occasionally. A backup file that turns out to be corrupted or incomplete is only discovered at the worst possible moment otherwise.