1. Monitor your infrastructure.
First of all, you should know what's happening with your website. If you're experienced with Prometheus/Grafana, you could use them, but if you’re not, it's not a problem; you can use any monitoring service, such as DataDog or any other SaaS service, and set it up really quickly. If it's still hard, use pingdom or site24x7, at least to check that your website is still available.