Remove the negative battery cable.
Drain the cooling system.
If equipped with drain plugs on the engine remove them. They would be located at the bottom of the block near the oil pan.
Remove any components that restrict access to the freeze plugs, like the starter or motor mounts.
Wearing proper eye protection, tap the bottom edge of the freeze plug with a punch and hammer. This should tilt the freeze plug, not cut it. Then use pliers to pull or pry the freeze plug from its bore. Another method is to drill the freeze plug and use a slide hammer, but often there's not enough room to do that.
After the plug is removed, clean the area completely. Coat the freeze plug and/or bore with gasket sealant.