First make sure both cars are turned off and so are their equipments like radios, etc. also unplug anything that is connected in the lighter plug.
Read your battery carefully make sure you know which side is Positive and which is Negative.
Check if there are any cracks on the battery, if you happen to find a crack on the battery then don't continue for it will explode if you continue.
Try to clean any corrosion around the dead battery's terminal.
As much as possible wear a protective eyewear
Now to connect the cables.
STEP 1: Connect one end of the cable to the Positive(+) terminal of the dead battery.
STEP 2: Connect the other end of the Positive(+) cable to the Positive(+) terminal of the good battery.
STEP 3: Connect one end of the Negative(-) cable to the Negative(-) terminal of the good battery.
STEP 4: Connect the other end of the Negative(-) cable to a NON PAINTED metal part of the engine on the dead car.
So why didn't we connect our negative cable to the negative terminal? It's because we usually avoid connecting it directly to reduce the chance of explosion, connecting our cable to the negative terminal is the last resort.
Now to Jump Start your car, first start the engine of the good car then let it run for a while rev it a bit, after a few minutes you can now attempt to start the dead car.
That is the standard method, there is a much safer way but sometimes it doesn't work, anyway here is the safer method, after connecting the cables correctly as stated above, next is to start the good car rev it for a while until the dead car battery is charged enough to start, then turn off the good car and disconnect the cables, now try starting the dead car, if it didn't work then you should try the first method I mentioned.
How to disconnect the cables? simple you just reverse the step, here are the step by step:
Important: Becareful not to let the cable clamp touch each other.
STEP1 Disconnect the Negative (-) cable from the engine block of the dead car
STEP2 Disconnect the other end of the Negative(-) cable from the Negative (-) terminal of the good battery.
STEP3 Disconnect the Positive (+) cable from the Positive (+) terminal of the good battery.
STEP4 Disconnect the other end of the Positive(+) cable from the Positive (+) terminal of the dead battery.
Jump Start Supercars