Which metrics matter most on a multi-project VPS?

When I ran multiple apps on one VM, disk I/O was the first thing to betray me, not CPU. A single chatty service with a messy logging setup tanked performance for the rest. After that, I started tracking I/O wait, network jitter, and CPU steal to see if the hypervisor was being noisy. Baseline monitoring plus short stress bursts help reveal patterns. And when I need to compare packages or upgrade tiers, I usually check configs here to buy vps  because it makes it easy to see how much disk speed and guaranteed resources improve with each plan.