Organize/keep track of everything you take off.

Dont get rid of factory parts you might need them later when something breaks.

Extensions and flex joints are your friend when using wratchets.

Dont use a standard socket when the bolt is metric/ vise-versa, no matter how close the fit seems.

Having a bench/large table to work off of is very helpfull and makes it easier to keep track of parts that you take off/ put on.

always use jackstands when working under a car.

Wear Eye protection when under the car, because dirt falling into the eyes is the worst.

People with lots of tools make good friend, but respect their tools and give them lots of beer in exchange for their use. especially when its family members with the tools.

Thats what ive learned in the few short years ive been working on cars.