My only advice to you, is get some legit trainees this season. So you can go into IV with a training schedule, because trying to establish training in Div IV, will be shitty. Pick and Choose your matches. I got lucky, i had a pretty decent team going into 4, and the other division during interleague sucked balls.
But, my best advice is gather up some trainees, play defense, and pick your matches well. And you will not relegate unless your not suppose to be in IV.