About the mind-boggling fifth dimension of our car-life we call the Service center (the other dimensions being the driver, the front passenger who presses his feet on the non-existent brake, the rear passenger who always knows the wrong direction and the car which develops a mind of its own) where we take our cars on an average of 3-6 months for something called "free" but nevertheless we end up paying, here are a few things I thought would make your life easier, just like it does mine.
Before taking it for service:
1. Make sure you take a walk around your car, inspect it externally to see if everything is alright. Take a quick note of major scratches etc. Inspect the interior for any dirt on the seat etc. Cuz you are taking it to a place where there are quite a few grease monkeys and you don't want dings and grime on your car.
2. Make note of the odometer reading and also don't fill up your tank before taking it to service. You'll never notice the 1 litre that could be suctioned out.
3. Remove your expensive audio system, sunglasses etc and take them with you if possible. If not, lock them in the glovebox. You sure don't want a mechanic pimpin your dolce & gabbana, thumpin to Jay-z, driving down the freeway picking up chicks you couldn't.
4. Be on time for the service. Don't go late and start arguing with the service guys that its the traffic. Its never the traffic. Its always you starting late. Try to get the service done on a day where you don't have too much to do, especially midnight customer calls etc.
During:
1. Make friends with the Service guy. Know his name and his mobile number. Insist on talking to him as much as possible. Introduce yourself and if possible, share your business card with him. This relationship should be kept professional / business casual and so ensure you don't take it too far like inviting him over for drinks etc.
2. While you are chatting, please don't make statements such as "I have no idea how this works.." or "I am in a rush, can we get this done quickly?" - usually these are the times when corners are cut to ensure a "quick and prompt" delivery.
3. Make sure you take a quick look at the Service manual to check if the things listed are being checked by the Service agent in his paperwork. Also, let him know if you want anything else inspected.
4. Never pay upfront. Its a service. The company is not poor enough to bank on your 400 Rs to get a part for the car. Also, if any part is "recommended' ask questions to thoroughly understand why its being changed, what was the damage on the old one and how long will the new one last. Also ask to see the old part if you are feeling suspicious.
After:
1. Be there on time to pick up your car. As much as possible, don't leave the car overnight in any service station.
2. Request a copy of the checklist. Make sure you understand what's been done and what's been changed.
3. If you are getting warranties for any product, please get it stamped and put it along with your service manual immediately. Not in the dark bottomless hole you call pocket.
4. Make sure stuff in your glovebox is still there and all switches, wipers, lights etc are functioning. A fuse or a wire may have been accidentally pulled out and it will be a hassle getting it back there just for that.
5. Thank the Service guy and leave. Don't hang around there talking about your car experiences and knowledge, offering your intuition to every car problem. Refer Point 1: Business casual relationship.
Take care and have a wonderful service experience.

And if you are waiting in the lounge, read your car manual to pass your time. You may become a service mechanic yourself, who knows!
Please feel free to change / add / delete anything mentioned above.