Best procedure for next year would be that the host location provides a list of countries that request a Visa. Every embassy should have this information available.
It's not knowing that a visa is required that's a problem. It's this:
1. Purchase flight so that visa request can be made. (Some countries require you to have the flight already.)
2. Visa request denied.
3. Flight rebooked through alternate itinerary that visa can be obtained for.