Not having populist demagogs reach significant power would be a nice start. Though I'm not sure if the migrant "crisis" is actually the cause or just a symptom for deeper issues.

Not dividing population into two sides on the refugee issue, not breeding so high level of internal resentment. Having a bit more united front on the issue. I'm half-convinced that the way the current refugee crisis ended up being handled was much more disruptive to our internal politics than just letting them all in would be to our economies.