ABOUT AUTO PAINT - PREP'ING FOR THE BODY SHOP
HOW CAN I (AND SHOULD I TRY TO) GO ABOUT PREPARING THE CAR
BEFORE I TAKE IT TO A PAINT SHOP.

Caution is advised on this subject, since it is easy for someone who is inexperienced to create more work by attempting to do too much them selves.
Body shop costs are calculated from the hourly rate the shop normally charges multiplied by the hours required to do the work based on Mitchell Guide Flat Rate manuals. Let's say the hours required to re-finish a car is quoted at 23 hours, multiplied by a shop rate of $42.00/HR, plus an additional charge of $19.00/HR for paint materials, we would arrive at a cost of $1403.00 plus any applicable taxes. Body work is extra, usually quoted at the shop labor rate plus an additional charge of $9.00/HR for shop materials.
To reduce some of the labor time, one could remove all chrome and trim that has to be removed for painting. If the sheet metal is straight, then sanding with 180 grit or finer would also cut down the labor costs. But then again, putting additional divots with the sander, or denting the sheet metal while removing the trim will only increase the labor hours. I would suggest consulting with the body shop that you intend to use, as to what you can do. How much and what you decide to do is at your own discretion.