Attack Venom from behind when he is at the helicopter. You can usually get in 5 hits safely before he attacks. Once you attack him, use webzip to get as far away as possible. Venom will then jump towards you and either attack or throw objects. Get in quickly and unleash another flurry of combo hits on him. He will then return to the helicopter and you must repeat this process, only later you will have to avoid the fire that spreads on the roof.