I know this may sound like I'm trying to keep you from dooing your own maintenance, but the "best" way to change the coolant is to have it done by a shop that uses a vacuum recovery/ recharge system. They are the most affective way to replace all the coolant, plus there is no mess to clean up and no hazardous materials to dispose of.
If you feel like dooing it your self, the first thing you will need is a couple empty 5 gallon buckets and a good drain pan. Start by draining the radiator. Then using a floor jack lift the rear of the vehicle and remove the lower radiator hose. Next remove one of the heater hoses and using your garden hose flush all the old coolant out of the engine block. Make sure you catch anything that comes out of the radiator and engine and dispose of it properly. Now you can reinstall the lower radiator hose and lower the rear of the vehicle. Leave the heater hose disconnected for now. Be sure the drain on the radiator is closed and begin refilling the cooling system with 50/50 etholyne glycol (antifreeze) and distilled water mix. Fill the system until coolant starts comming out of the heater hose (leaving this off allows any air trapped in the block to be forced out). Reinstall the hose, finish filling the radiator and remember to check the overflow. Now start the engine and turn the heater on. Allow the engine to reach opperating tempature, while keeping an eye on the coolant level in the radiator. If it starts to overflow, install the cap. Once the engine reaches opperating temp. shut it off and allow it to cool. Once it has cooled recheck the coolant level in the radiator and the overflow and top them off.
