As other said, we know very little about the war. One-Emotion8482's point about destroying the industry might help. Since it's the middle of the war, and the Geth are already hell-bent on extermination, it's probably a good idea. Ditto for evacuating as many Quarians as humanly (quarianly?) possible.
Instead I'll focus on the geopolitical aspect. Rannoch is dangerously close to the Terminus Systems and to the Batarian Hegemony. While almost literally anything would be better than having 99% of your population exterminated, even if we do manage to defeat the Geth, it's likely we'd be enslaved and picked off by opportunistic pirates after our nation has been crippled. Which is not a desireable outcome either.
I think the best bet is a massive propaganda campaign, try to publicize to the rest of the galaxy how the Geth are exterminating the Quarians, and how the rest of the galaxy is probably next (Not really, but they don't know this).
Particularly, I'd target the Turians for this. They have the strongest military, and they're dextro-amino acid like the Quarians. They're in a good position to send aid and supplies. I'd do everything I can to pull them into this war.
It's hard to say what it'd take to get them involved. But it's pretty important. Even if it means bending the knee to the Turians, and becoming a Client State to them, much like the Volus. The Quarians could fill a useful niche for the Turians, as their engineers, much like how Volus are their bankers. The Hierarchy also obtains a forward operating base near the Terminus and such. Distasteful? Certainly, but better than near-extinction.
If I manage to survive and succeed, then I would probably try to get the galaxy prepared for the eventual Reaper Wars. I think the Morning Wars happened in the late 19th Century, so there's some time.
I'm split on whether or not it would be a good idea to bring Humanity in earlier. Make contact with the Empires of Europe and prevent the holocaust and the world wars was we know them? Let them happen and let the SA form? Unsure there.