This part is simple, don’t make promises you can’t keep. Sweet talking your way through a difficult interaction may make today easier, but will further compound the problem down the line.
Here are "5 Tips for Successfully Setting Realistic Expectations for Clients" which can assist you in effectively managing client relationships:
- Know your limits.
- Don't over promise.
- Explain potential obstacles.
- Choose flexible deadlines.
- Maintain open communication.
The second article goes further into detail regarding the Do's and Don'ts of setting customer expectations:
DOs & DON'Ts of Setting Customer Expectations - The Ritz-Carlton Leadership Center