1. Don't rush to judgment. We don't know the full story yet.
2. If it's fraud, give back whatever money can be given back.
3. If it's fraud, make it clear that the EA community does not support a philosophy of "making money on criminal activity is okay if you donate it to an effective charity".

One thing that I think would be helpful is a discussion of the corrosive effect of certain kinds of dishonesty and criminality on the communities we live, big and small. Some kinds of acts tend to weaken the trust we have of our communities thus crippling our abilities to act together, which is often critical.

This is why, even from a pure utilitarian perspective, there should be a strong presumption against certain kinds of dishonesty and criminal activities. The knock-on effects, upon discovery, are often orders of magnitude larger, and negative, than the direct effects. And, since we think in EV terms, when we incorporate this into our decision making, criminal and/or dishonest decisions are seldom justified.

Perhaps the discussion of the perils of using socially corrosive behavior to further one's ends is discussed in EA, but I have not seen it much in my experience.

One thing we can do as a community is come up with ethical principles for earning to give and expect our donors to adhere to them.

It's good to be more ambitious and risk-loving than most entrepreneurs and other people who aim to make money, but you have to do it responsibly. Being cooperative and acting with integrity are in CEA's guiding principles; we need to articulate publicly and prominently that they also make the world a better place. Personally, I lean towards rule utilitarianism, so this view is second nature to me. But we should be able to justify this view using the thinnest possible version of consequentialism.

Also, good risk management is important to every successful business regardless of its risk appetite. FTX was insanely over-leveraged and exposed to wrong-way risk, which made it vulnerable to imploding in the way it did. Risk is fine; stupidity is not.

Absolutely never become involved with cryptocurrency in any way, shape, or form ever again. It's poison on every level. It's environmentally devastating. It enables crime. And, well, it's a Ponzi scheme.

A good read about crypto: https://www.currentaffairs.org/2022/05/why-this-computer-scientist-says-all-cryptocurrency-should-die-in-a-fire

EAs should:

1. Make clear that they oppose what has happened. 
2. See if anything can be done to repair the situation. For example, consider returning any funds that were obtained from any fraudulent activities (which may require raising funds from others who were not involved), or maybe even offering legal aid for those affected by any fraud.
3. Re-evaluate whether EA per se is still a positive ideology to be promoting (as compared to promoting particular academic fields, like AI safety, and important ideas, like existential risk.
4. In any EA-like community that continues to exist, we need to encourage people to behave in a more trustworthy manner. People should be praised for considering a range of moral perspectives, and deferring to others views on risky projects, whereas we should distance those who have misbehaved - Eisenberg, Vassar, Reese, and so on.
5. Require more verification from people who tend to behave in a naive utilitarian way. So long as some naive utilitarians are liable to behave fraudulently, utilitarians should be held to a higher degree of transparency in entrepreneurial endeavours, in order to raise comparably sized investment rounds, or to take on comparably-prominent public roles. And this is just what utilitarians should reasonably expect, based on their track record.
6. Re-evaluate whether particular activities currently pursued by EA are meet these new standards of trustworthiness. It would be good to consider whether to press on with party-politics and youth outreach, for example.
7. Listen more to people who were rightly worried about FTX, and less to people who weren't worried about it, or who worried excessively about other stuff that didn't matter much.

I wrote a post on damage mitigation ~2 days ago, but it got brigaded by a bunch of poorly-informed, overconfident people:

https://forum.effectivealtruism.org/posts/HJbd7Fwzh6BZGK6En/two-key-strategies-to-mitigate-the-damage-from-losing-ftx-2