Looking for tips to launch a performing portfolio strategy as a Key Account Manager

Hey guys, I’m Leonardo and I’m new in key account management.
I manage a portfolio of 100 key accounts (mostly e-commerce and retailer) for a fintech scale-up skilled in the Buy Now Pay Later market. I need to reorganize my portfolio and activities to help partners to perform better and reduce churn.

Any tip? Any Key account manager around?

Would be great to hear from you guys!