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.)
I think it's a better idea to first identify ideas that are better than doing nothing - which in itself can be difficult! - and then prioritize those.
I think there are talented people who could be convinced to work on the long term future if they are given a task to do which is uncontroversially better than doing nothing. I agree it's better to prioritize actions than just work on the first one you think of, but starting with a bar of 'optimal' seems too high.