Basic question about diving.

When team is coordinated and close to each other, what should I actually do? If I try to get just one, long range enemies get me before I escape, maybe I need to think in advance and always look in advance for eacape routes, like angles or hallways. Even with that given, in some cases it seems like there are no escape routes.

Second thing is dash and portal combo attack, should I avoid it when they are grouped up? Save one of them for the escape?

Thank you in advance for any answers.