how not to be scared of your dog?

Well i love my dog. he is a pit lab mix. i mean i take my time with him and every thing but sometimes thats not the case . when he stays outside flies bite his ears so when i try to put fly repellent on him he runs away and growls then when i go up to him to put it on his ears he charges at me and when i walk him he pulls me foward a lot my dad says to hit him when he does not listen but i know thats does not work dogs dont understand punishment also every time i run pass him he tries to gnaw on my ankles wierd you know