How do I make good grades in culinary school?

Hi, I'm a fourty year old grill cook with 10plus years experience. I've worked everything from fast food, mom and pop owned family restaurants, bar and grills, to cafeteria and buffets. I've worked really hard over the years at two jobs sometimes three to support my loving nurse perusing wife and two boys over the years and never have made much money just enough to get by paycheck to paycheck. Currently I work under a chef at my day job as a grill cook at a cafeteria and by night I work the show grill at a buffet in my home town. My day job will pay for some of my culinary education and I can't wait to get started because I really want to be a chef by the time I'm fifty or possibly run my own restaurant. My question is what should I study now to get me prepared for school and what do I need to focus on to get good grades in my culinary courses?