The easy ones, done well.
WHY RESPOND AT ALL
It shows you read them It encourages others It adds content to your profile
WHAT TO WRITE
Short and specific.
Thank them, reference what they mentioned.
WHAT NOT TO WRITE
The same response to every review.
Identical responses are obvious and reduce the value.
A GOOD EXAMPLE
"Thank you. Glad the installation went smoothly and that the timing worked for you."
Specific to what they said.
A POOR EXAMPLE
"Thank you for your feedback. We appreciate your business."
On every review.
LENGTH
One or two sentences.
TIMING
Within a few days.
WHAT TO AVOID
Selling in the response Excessive enthusiasm Adding a promotional message
WHAT TO DO IF THEY MENTIONED SOMETHING SPECIFIC
Acknowledge it directly. That demonstrates you actually read it.