In the early game make sure and upgrade your zerglings so they can burrow underground. Make some Zerglings. Use your eyes and judge about where seige tanks would have to be in order to attack your defense. Move your zerglings there. Then burrow them underground. When the seige tanks come up to attack you. You wait for them to go into seige mode and then unburrow them. With 12 zerglings 4 to 5 tanks can be demlosihed. If the Terran enemys happen to have mucho tanks stradigey you will need more zerglings.

CreepColony's Opinion: This may work against newbies, but good players will comsat the area before sending their tanks there.