Heh, you can't beat the advice of a veteran like me
Be a stormie or engineer. When your capturing the first CP, hide behind those pillars. When your done, run through the plants by the water to get to the CP where the tanks spawn. clear the enemies and crouch and hide in the water fountian and capture the cp. become an engineer, rush to the next CP, hide behind the pillars and heal your self. When your done, rush the tank up to the computer and destroy it. Need anymore advice?