Consider all the actions possible tomorrow, which individuals or groups could take. Are there any which would "obviously" (meaning: you believe it with high probability, and you expect that belief to be uncontroversial) result in decreased x-risk?
(For example, consider reducing the size of Russia and the US's nuclear stockpiles. I'm curious if this is on the list.)
(I include "which individuals or groups" could take because I am interested in what actions we could take if we all coordinated perfectly. For example, neither Russia nor the US can unilaterally reduce both their stockpiles, and perhaps it would increase x-risk for one of them to lower only theirs, but the group consisting of US and Russia's government could theoretically agree to lower both stockpiles.)
Increasing the ease/decreasing the formality of world leaders talking to each other as per the Red Phone. World leaders mostly getting educated at the same institutions helps enormously with communication as well, though it does increase other marginal risks due to correlated blind spots.
Biorisk mitigation becoming much higher status a field and thus attracting more top talent.
Pakistan not having nukes.
When I was studying maths it was made clear to us that some things were obvious, but not obviously obvious. Furthermore, many things I thought were obvious were in fact not obvious, and some were not even true at all!