Maybe I am wrong, but from what I've read and done most of the information I've read in this thread is either completely inaccurate or lacks the details needed to be understood. Compound exercises are great, but the you have to include isolating exercises as well.
1. Eat. Eat a lot. You have a higher metabolism than most, and thus you burn through your resources (energy, protein, amino acids) than others.
2. Fat disappears fastest from your shoulders and slowest from your stomache. Cardio will work, but the first 45 minutes are just burning reserves, you need to do cardio for longer than an hour in a day, not all at once nessacarily, but you should break and 1.5 hours of cardio to expect to burn. Think numbers, if you run for 15 minutes youre going to burn between 100-200 calories, which when you look at your intake is a can of Pepsi.
3. Eat. Eating more is great to gain weight, but if you dont do anything you wont get anything but fat. Especially if its all junk. People often eat less to lose weight, or eat less and exercise. Both wreak havoc on the body. Exercise and eat good. Having some junk is ok, if you dont care about being cut.
Great sources for what you need are Chicken, Steak, Fish, Pasta, Rice, Variety of Vegetables, Eggs, and WATER.
4. Working out for goals! If you want to get big, you want mass exercises. Power? Explosive exercises. Strength? Slow and heavy. Cut? Light, fast, and high reps.
5. You need to have a strong core (torso) foundation when working out for *any* gains. Work on planks, trunk twists, and the big 4 exercises.
6. Form is important, as is using free weights. Balance is key, and if you are in a machine your body can't properly (or rather, as effectively) build your stabilizer muscles to help give you proper balance, which will affect over all strength.
7. Creatine doesn't give you as much size as everyone says. And by everyone I'm talking about how people think it does cause that's what they heard. Creatine is great for explosive energy for 1-2 reps at most in each exercise, and thats it. It helps with endurance and some marginal strength boost, but it wont make you bigger because it's creatine, it will make you bigger because you were able to push out one or two more reps.
8. Always follow the big 4: Bench (preferably incline but flat is good too), Squat, Deadlift, and Olympic Press (clean and press.) They will give you the best strength and size gains for your work. Just be sure to stagger them out, and give at least a day rest to heal.
9. Stay consistent! On/off or long breaks all the time will not help. Some breaks are good, but it should never be longer then 2 weeks, hell even 1 week is pushing it.
Go to ironaddicts:
http://www.ironaddicts.com/forums/ for some real information, and a great bunch of guys all around. I've been learning a ton from them, and my strength/size/health has grown leaps and bounds compared to following most of the ideas posted here.
Since youre whats considered a "hard gainer" go here:
http://www.ironaddicts.com/forums/forumdisplay.php?f=65
And for gaining size and strength, try the Simple Power Routine:
http://www.ironaddicts.com/forums/showthread.php?t=8050
Using that routine I went from a 200lb x 10 "1/2 squat" to a 285lb x 12 "box squat" in about 3 months; and a 135lb x5 deadlift to 255lb x 8 in the same time.