How can I monitor Varnish performance and identify potential causes of cache errors?

Monitor Varnish using tools like `varnishstat` and the Varnish web interface. Look for metrics such as cache hit ratio, request latency, and error rates. Analyzing these metrics can help identify bottlenecks and potential causes of cache errors. High error rates or low cache hit ratios can indicate problems with the Varnish configuration, network connectivity, or cache invalidation.