The best way is to pick up a prestone flush kit from Advance for 3 bucks. Put it on the top heater core intake hose (the one that goes to the tstat housing)
Take the top rad hose off for a renix or just the cap on the others. Dump your coolant in until it wont take any more. Then lift that flush T as high as you can, use a funnel and keep pouring it in until it wont take any more, burp the top hose as you go.
Fire it up and let the tstat open, and if you have the sensor on the back of the head you want to park it downhill, no sensor? park up hill, now shut er down and drink a beer. Then see if its cool enough to work on...if not then you drank your beer too fast. Get another beer.
Now crack that sensor until coolant comes out, any air in the head will come out.
The up hill method, take the t cap off and fill, close it up then burp the hose, when you do that a few times the air goes to the t and into the overfill. After you run it for a little bit you can lift the T and fill it there. It will probabally just go to the overflow tank.
This method works great, I love using that prestone flush kit. the cap is the highest point in the system.