Advice Best Practices for Using Dual SIMs While Traveling?

I'm new to using dual SIMs for traveling and could use some advice. My Android phone supports a physical SIM and an eSIM. I currently have a Verizon SIM and plan to get a local SIM when I travel abroad. How do you manage your dual SIM setup to avoid roaming charges while ensuring you're always reachable? Any tips on which SIM to use for data and which for calls? Also, how do you handle switching between them? Looking for any best practices or lessons learned from your experiences.