There isn't much that we can provide for you in this section as it is mostly just common sense, even if you have bad customer service skills (you are in the wrong business though). Fortunately, CompTIA's exam objectives list most of what you need to know and we have summarized these points below:
Using Good Communication Skills:
Use clear, concise and direct statements.
Clarify customer statements with relevant questions.
Avoid terms that will confuse the customer (acronyms, jargon).
Always listen to what the customer is saying.
Keep a positive attitude.
Don't argue or get defensive with a customer.
Do not make light of customer problems.
Do not insult your customer or call them names.
Avoid distractions when talking with customers. Give them your full attention.
Respect the workplace policies and property of your customers.
Not on the list, but I would add:
Keep time committments or communicate changes with the customer as soon as possible.
Well, that is it for our study guide. Best of luck to you on your exams!