Everyone responds a little differently to foods. MT's outline is definitely a solid example. Here's some of my ideas.
I actually respond better to diets higher in fat, and a little lower in the carbohydrates. I'm prone to storing carbs as fat it seems. After just coming off a fat loss diet, my calories are about 25% fat, 25% carb, and 50% protein. I also limit my dairy intake a little, because it's a possible allergen and I find myself bloating a lot when my dairy is excessive.
As you said you're going to just begin hardcore training, I think it's important to keep it simple. Don't worry too much about exact amounts, eat until you're pretty well full and start to feel you shouldn't continue eating. Go ahead and eat tons of protein, a lot of carbs, and also some fat with each meal, at least 6 of them a day. Also vegetables with every meal, I feel is very important.
Here's food choices that I usually stick to:
Protein: any relatively lean meat (beef, chicken, fish, turkey is all good), eggs, cottage cheese at night, whey protein or protein blend supplements, some milk, and yogurt is a good complement to anything
Fat: almonds, peanut butter, EFA supplements
Carbs: vegetables! (I use lots of green beans, asparagus, spinach, and collard greens), rice (any), potatoes or yams, cornbread, grits, oatmeal, and some fruit if you like (I only have grapefruit)