Grafana Cloud provides guidelines for creating effective alerts on synthetic monitoring metrics, utilizing predefined alerts and PromQL expressions for various monitoring needs such as uptime, reachability, average latency, and error rates. The platform offers a predefined alert on the probe_all_success_sum metric, while users can define alert thresholds for specific metrics like reachability and error rates, both generally and by individual probes. Alerts are built using PromQL expressions that evaluate data over a specified time and can transition from pending to firing states if conditions persist, with users encouraged to test and tweak thresholds to ensure accuracy. Grafana Cloud also offers documentation and resources for further learning, along with a free account option to explore its features.