Act now, act with speed.
Protect vital core of the business.
Make sure you have 18 months of cash on conservative revenue forecast.
Defer facilities expansion.
Re-evaluate R&D spending.
Re-negotiate any and all contracts, including leases.
Everybody in the company ought to be selling. (The products, not the stock.)
Give equity bonuses instead of cash to employees.
Secure cash - in Treasuries, government based securities, not money funds; we could lose a major bank.
For revenue plans: figure out the leading indicators that will tell you about repeat opportunities.
Over-communicate with everyone. Make sure everyone knows where things stand. And do not cut hope.