Attack: Make him tired first without tiring yourself out, save your hardest punches for when he's most vulnerable. If you get a chance, punch him as hard as you can in the tailbone area, this can hurt A LOT and will take him by surprise, if he holds it in agony, deliver another fist to his stomach. Another sweet spot is right between the eyebrows, if you punch him there he may become very disorientated for a couple seconds, leaving him very vulnerable. I'd say if you're going to kick, aim for the knee area, it'll be hard for him to grab your leg and he may lose his balance.
Defense: Just stay out of his reach, do not get held down in any way and if you're going to kick, keep it low. (if he grabs your leg in the air you're screwed).
Do you mind telling us why you're going to fight him?