Possible Clues:

• What the fire department recommends
• Workplace motto
• Cautionary workplace axiom ... or a hint to the starts of the answers to starred clues
• Cautious person's motto
• 'Put caution before anything else!'
• 'Be careful!'
• Slogan advocating caution
• Motto for the cautious, and a hint to the starts of 17-, 23-, 39-, and 50-Across
• Motto for the cautious ... or a hint to the starts of 17-, 28-, 37- and 45-Across
• Cautious — for example holding fund-raiser without one European premier