This is going to be long. So man up and read it.
Get yourself oatmeal that gives you the most calories out of the smallest servings. Needless to say, these oats should be all natural 100% rolled oats, and nothing more. No boxes, flavors, etc. If the first thing listed on the box is how to microwave it, you've failed. Anyways, I found one that gives you 150 calories and 6g protein for 1/4 cup. Cook, add two/three scoops of Grow!, and some milk. The milk is mainly to help mix the protein powder, but it makes it taste better too. I use 3/4 cups oats, two scoops of Grow!, and 1/2 cup milk, so I get 700 calories and 43g of protein out of this easy to make breakfast. Hell, the timing is just perfect too. I make my school bag while the water boils, shower while it cooks, shave while it cools down, eat it and brush my teeth and I'm out.
If you eat sandwiches, load them up with as much meat as possible, and veggies. My school cafeteria is horrid, but they do have a free sandwich bar or w/e they're called, so I take two slices of whote-wheat bread and ninja about 6-8 slices of turkey breast (the other meats are all processed bologna POSs) and a buttload of lettuce, tomatoes, and pickles (I do hope pickles are healthy). If you can, make yourself sandwiches at home, and bring them to school for a snack, or for lunch, or both.
Inbetween breakfast and lunch, if you're short on time, your school is worse than the soup nazi, or you just can't down 20 slices of meat in two sandwiches a day, you can have a good snack with two-three Grow! bars and an apple. It's small, it has few calories, and getting the bulk of your protein from non-whole food (natural food you make yourself) sucks, but it's better than nothing.
Tuna is good, make sure you don't forget your veggies (again). I buy Chunk Lite in cans. Two cans gives me 300 calories and 65g of protein! That's a FUCKLOAD of protein for something you can eat in about 5 minutes. Eating it with bread is OK, make sure it's whole wheat, and again, DONT FORGET THE VEGGIES. I chop up 2-3 celery stalks and add it in the tuna bowl, and some fresh squeezed lemon juice for taste.
Talk to your mom/dad/whoever cooks your dinner about it. The more chicken and steak you get, the better. It's the easiest food to cook that contains lots of protein. Make sure to get your veggies in this one too. ANd if it's not some sort of meat, make sure it has protein.
Eggs are great too. You'll most likely need some egg whites too to get enough protein. I mix 4 eggs and 4 egg whites with two-three sticks of green onion (scallop??) and some herbs, and 1/2 cup of this delicious shredded cheese I buy at Demoulas. Quick and easy omelette, lots of protein, lots of calories.
Finally, check out John Berardi's 7 Nutritional Tips (or w/e the title is): http://www.t-nation.com/readTopic.do?id=459493.
The gist of it is this:
1 - Eat every 2-3 hours
You should be eating 5-8 meals a day. Plan it out so you get as many calories as you need. I need close to 4000 calories a day, so if I eat 6 meals a day (7:30 breakfast, 10:00 snack, 12:45 lunch, 3:30 snack, 6:00 snack/post-workout meal, 9:00 dinner), I should be eating about 600 calories per meal to get 3600 calories. Note, this is my GOAL. On an average day I barely break 3000 (but I do break it), but I've been able to eat more and more and in two months I will be eating 4000 calories a day.
2 - Eat complete lean protein with every meal (all essential amino acids)
Animal sources (poultry, beef, fish, eggs, cheese too I think) contain all the (9) essential amino acids.
3 - Eat fruits and/or vegetables every meal
This means eat vegetables every meal. One banana after your meal does not count. I don't even understand how people can skimp on veggies, I absolutely love them.
4 - All your carbs should come from fruits and/or vegetables (except for pre/post workout meals)
This one is weird. In his Massive Eating article, Berardi mentions that eating carbs long after your workout is OK (especially for dinner). MANY people here eat oatmeal for breakfast (I eat eggs for breakfast on workout days, oatmeal on others). So I don't know what to say about this one. Try to adhere to it, but don't go anal about it.
5 - About 30% of your calorie intake should be from fat, split up equally into saturates (animal fat), monounsaturates (olive oil), and polyunsaturated (flax oil, salmon oil).
For now, just make sure you get enough fat. Then worry about the more minute details. Cook in olive oil.
6 - Drink only non-calorie containing beverages.
I drink mineral water by the bucket. Others enjoy some green tea. The thing is, most calorie containing beverages are processed and pretty shitty. At the least, cut out soda and caprisun etc. etc. The only acceptable juice you COULD drink is OJ. But even then, many of the so-called natural freshly-squeezed juices are BS.
7 - Eat mostly whole foods (except pre and post workout foods).
As I said above, if you must, get calories and protein from some protein bars, but on the whole, use supplements and MRPs to SUPPLEMENT your current diet, not to make it.
Oh, and keep a food log. Anyone who makes fun of you for doing so should be kicked in the nuts and/or breasts.