Read, listen. There are a lot of great coaches willing to help you. Take some time and understand potentials, future stars, and scouting reports- getting a guy with high potential in the right places at DIII can make a huge difference. Try and see if you can hook up with a much better coach than myself that is willing to sitemail and help you through the first season or so- I'm not great, but I wouldn't be half as good if it wasn't for Daalt years ago, and my DIII conference mates today helping me out.
Last two things I say to people who started in GD- remember, even the great teams in HD rarely go undefeated. There's a lot of great coaches out there, and unless you have a very poor SOS, you will lose a close game or two (as you will win them). And make sure you understand the differences with promises in HD, as well as the difference in how WE and attributes gain.
Have fun!