Hi Sorina,
I'm very new to VMware but I can have few recommendations for you. As you know, all metrics in vCOps come from the vCenter. So you can take a look at this. There are some key metrics and troubleshooting in this guide.
After looking at this, you can create Heat Maps, Health-Workload Scoreboard and Top-N Utilization dashboards for troubleshooting. I think this will lead you to decide which metrics are important for you.