If you do not feel this way, or cannot answer some questions, do not offer to be a reference.

Because verbal references are the most effective, responding by telephone works MUCH better than e-mails. If you have a choice, be certain to follow up with a telephone call within 24 hours if not sooner. Turn on your "do not disturb light", shut the door and provide your undivided attention.

If you have been given the position specifics, or any detail regarding qualifiers or possible reservations that are critical to the employer, be sure to hit on those areas directly. Regarding technique...have a pleasant conversation, be certain to keep the dialogue casual and light.

The most common method of securing a reference would be for the information collector to ask, "What can you tell me about <insert name>." You must be able to articulate the necessary information, speaking about all the good qualities that come to mind. Please be certain to allow as much time as possible and answer all questions.
Typical questions include the following topics: professional relationship; title and capacity; areas for improvement; strengths; achievements; initiatives managed or launched; personality; failures; rapport/comportment; performance under pressure; talents to make tough decisions; work ethic/attendance; specialty; why they left company; would you rehire and anything else you can say about the person.

Example #1: The proper way a reference should answer the question "Have you noticed any areas that need improvement?", should be, "None that I can think of".

If a reference answers this question by revealing a true weakness, the reference will be viewed by the employer as being confused with their role. It can be very embarrassing.

Example #2: "On a scale of one to ten, with ten being the highest, how would you rank <insert name> in...?" If a reference answers with any number lower than an eight, they do not understand the responsibility involved in agreeing to be a reference. This is not an evaluation form. It is a reference.

Once you have delivered the reference, pick up the phone, call your friend and let them know what happened.
Most employers will classify references into four possible categories of quality:

Excellent: The reference called back within one business day, was enthusiastic, articulate, did not require much prompting and provided 100% positive feedback. A true admirer of the candidate.
Good: The reference called back within two business days, was enthusiastic, provided the requested information by answering questions with 90% positive feedback.

Fair: The reference called back within two business days, provided requested information with 80% positive feedback.
Poor: Any of the following: a) reference failed to return call within two business days, b) seemed guarded or did not know they were chosen to serve as a reference, c) could only verify employment, d) was inattentive or e) if they "threw the person under the bus" in any way.

Remember...agreeing to serve as a reference for a person that you respect, and then delivering a confidential verbal dissertation using all of your energy and enthusiasm, is wonderful way to assist a respected friend or colleague in need.