Let's face it, taking your car in for repair can be really intimidating. But, there are things you can do to help your mechanic make the fix easier and less expensive. With experience of the problem and some calm, clear communication with your mechanic, you can save time, money and aggravation. Here are some things to remember to help you achieve this goal.
JUST THE FACTS - When describing the problem, describe both the outside conditions (both road and weather) and your car's condition. This would include accelerating from a stop, decelerating to a stop, negotiating a curve, passing, or steady cruising. Also note what accessories were on in the car at the time (air conditioning, radio, etc.). State what you observed on the instrument panel at the time (warning lights and gauges). Have your maintenance records available.
NOTE A PATTERN? - Note whether or not the problem is constant or intermittent. The car's problem may be obvious (squelling brakes) or, if it happens only under certain conditions (a cold morning start), it may take more time to diagnose. You can pay your mechanic to observe the car's intermittent problem or do it yourself. You will need your sense of sight, smell, touch, and hearing to help you observe your car's problem. When you have gathered enough information about your car's problem then you are ready to pay a visit to the repair shop.
DON'T ASSUME - Instead of asking for a specific repair, describe the basic symptoms (following guidelines above). Let your mechanic ask further questions, and suggest the solution. If diagnostic testing is suggested, it's alright to ask questions to understand what the tests involve and how they relate to your car's problem. Let's say your engine is running roughly so you think your car needs a tune-up. Requesting that specific maintenance may not solve the engine problem since there are several causes of that problem. After the tune-up, your car is still running rough and you drive away blaming the mechanic when he only did what you asked him to do!
Keep in mind that when a diagnosis is made (such as a dead battery) that fixing the symptom (replacing the dead battery) could lead to the real cause of the problem which will need additional repairs (electrical component or alternator). Also, keep in mind that if the car is experiencing symptoms that would implicate multiple problems, your mechanic may need more time to identify the problems.
Having said this, it is important to remember that routine vehicle maintenance will noticeably cut down on the number of unscheduled "emergency/problem" visits to the repair shop. Having regular brake inspection, filter replacement, transmission service, etc., will remove potential problems from arising between recommended service intervals. In the long run, this will save you money.
A professional, competent and ethical auto repair shop can and will tackle and repair a vehicle even if misleading information is provided. However, clear communication and expectations for your vehicle's repairs will save time and money.