Here's my attempt at a summary of what needs to be done:

Basic enabling technologies, computers, software, networks, AI, biotechnology, nanotechnology.

Medicine: better treatments for viral diseases, cancer, aging.

Energy: anything that has prospects of actually replacing fossil fuels. Solar electric and algae-based biofuels currently looked like the most promising lines of development as I see it.

Space: anything that could shorten the time during which all our eggs are in one basket.

And I see three major ways in which individuals can contribute:

Personally work in one of the vital areas.

Make money and spend or donate some of it to support people who are doing such work.

Last but not least, this is a marathon not a sprint: take the long view and raise children who can do one or more of these.