A good place to start is to major on the majors:
Always keep in mind the ability to stick to the plan when you are setting it up.
Calories in vs. Calories out is going to give you the biggest return on investment.
Eat real food whenever possible.
Without knowing your friend, the basic process I would do is this:
Start with just getting in the gym. Strength training can jump start things in the right direction.
Maintain the current food intake and start making small tweaks.
Choose food you make over food you buy at a restaurant whenever possible.
Eat vegetables with your meat.
Personally, I've found small adjustments work best for me. As to macros, keep it simple.
1.8 g protein / 1 kg target body mass (when in doubt use your current body mass) -- 0.8 g protein / 1 lb for Americans
Carbs and fat in the right proportions to keep you satisfied.
At least 20% of the calories should be from fat
I find I do better with a diet heavier in carbs, but it wasn't always that way. Listen to your body. If there's a lot of fat to remove, then adjust your calories down by 100-200 kcal per day. If you eat more protein it won't hurt you, but it won't help either.