1. Numbers. Support your assertions with facts, not rhetoric. If you don't have numbers (eg actual costs of $40,000 vs planned costs of $35,000), then apply solid logic (eg if this, then that).
2. Relationships. Build trust. Don't spin a message with optimism or pessimism. Be candid. Scale your message to their level (don't burden execs with details; don't burden staff with generalizations).
3. Own it. Anything that's not going right is your fault, regardless of whether it's somebody else's fault too. Don't shift the monkey to others. Keep it. But actively seek the creative engagement of others in the matrix.