Yeah - wear an old vinyl or leather glove, and eye protection because the stuff will be hot. There are two ways to get the old coolant out:
1> remove the block drain plug(s) in addition to draining the radiator - very messy and you will get splashed.
2> repeated drains and refills with water (preferably distilled or de-ionized) until the effluent runs water-white clear. By using distilled or de-ionized, you won't be introducing any dissolved minerals into the system. Calcium is especially bad because it tends to form scale. Do NOT use ion-exchanged softened water. It's full of sodium and that's even worse because it promotes rust in iron and corrosion in other metals (yes, even aluminum will corrode). After each refill, idle the engine until the upper radiator hose is HOT - that's your indication the thermostat has re-opened. Four or five flushes are usually sufficient. Five or six gallons of cheap WalMart distilled water should be more than enough. Make sure the heater valve is set to its hottest setting to assure that the heater core is flushed, too. Once you're satisfied that the old coolant has been flushed, add whatever antifreeze concentrate you've chosen and use a needle-type coolant hydrometer (Prestone and Victor make good ones for about $3.50) to adjust to a 50/50 concentration. Afterword, drive several miles (with the heater control valve set to hot - you don't have to run the fan) to purge the system of air*. Shut the engine down and wait until it's cold, then check the coolant level at the radiator cap. If it's low, top up with a 50/50 mix. Also adjust the level in the puke tank to where it should be when cold. For the next several days, check at the radiator when cold and top up if necessary.
*Check your owner's manual - some cars have an air purge screw to simplify this operation.
