Write do's and don'ts for handling a PR crisis. Make them directive and easy for anyone to understand and follow.
Do:

Assume "worst-case" outcomes for planning purposes.
Inform key audiences regularly and accurately from the outset.
Ensure communications are candid, accurate and timely.
Focus on concrete actions being taken to understand or address the issue.
Retain control of the story. Both positive and negative information needs to come from the company to help assure a transparent posture.
Provide information that's relevant to the public's interest rather than just the company's.
Consider seeking third-party support to help explain the crisis to various audiences.
Explain the situation directly to key audiences using the channels that are familiar to them. 
Where appropriate, contact public officials and leaders proactively. Keep them informed throughout the process.

Don't:

Be silent or make “no comment” statements — they are often interpreted as admissions of guilt and lack of preparation.
Make "off-the-record" statements — there is no such thing in a crisis situation.
Speculate on anything or provide incomplete information. Stick to the facts.
Let erroneous information or ill-informed opinions go unchallenged.
Release sensitive or proprietary information.
Try to minimize the problem, but also don’t make it a bigger deal than it is. Match the level of your response to the severity of the issue.
Rely on communications alone to fix a crisis. You have to address the issue that led to the PR crisis in the first place.