Need to plan for a crawlspace clean-up and encapsulation

Hi!

I'm experiencing high humidity and some bad smell in summer and very dry air in the winter.
I think most of the issue comes from the crawlspace, it's vented and it looks like there was a vapor barrier in place but it was there with no tape so it's all over the place now. With big areas of the crawlspace completely uncovered.

There's no insulation at all on the joists, neither on the subfloor.
Just bare wood and concrete blocks.
I'll also have to fix the two access doors as the concrete around them is crumbling.

What should be a step by step plan to tackle this?
Is it something that can be done gradually over some weekends or should I do it all start to finish in a few days?