This is a tip for you, if you want to use GLA. GLA has a bad defence, even you've used many stinger site to keep your place your enemies are still able to attack you. So, you must not think that your defence is strong. But you can solve it by taking the enemy's technology. U can make jarmen Kell in your barrak, then you command him to go to your enemies base carefully. You must find an enemy's bulldozer. You shoot the driver and take it. To make you easy, after taking it. you must build a command center use that bulldozer. Although your bulldozer has been destroyed by your enemy you can continue the buildeng by your villager, and you can improve your power to defeat our enemies.