heavy weight + high intensity + low volume = big gains.
Someone made a great point about getting your diet dialed in. The Austrian Oak (Arnie) once said that 10% of growth occurs in the gym, the rest is what you do outside..eating, and rest. If you don't have both of the latter dialed in, and are not eating enough nor resting enough to give your muscles time to repair and grow, you simply..won't grow, or not much, no matter how hard you hit it in the gym, or what you do.
Think of what's worked for you in the past, and make decisions for yourself; there is some great advice and alot of knowledgable people on this board, but your best source of knowledge is YOURSELF. What will work for you, is not what's going to work for the next dave, john, or joe, and what they do for themselves cannot necessarily apply to your training. There are time revered techniques and training, that are very much applicable to today:
Hypertrophy will occur in the 8-12 range of repititions yes, but the man wants to bulk folks. Strength is if the most solid foundation for size. Do you ever see a fellow benching 405 for 5 that has a small chest? Never.
What i would prescribe for you sir (and you do NOT have to listen to me)is for your heavier compound lifts, shoot for a 3-5 repitions range if your comfortable working with that --and if not, or if your new to training (and i would NEVER prescribe these rep range for a new trainee in the gym, only someone who has a solid strength base already).. do 6-8 repititions, NOT 8-12 if your trying to put mass on your frame. Alot of your growth occurs when your firing your muscles in the 80%-1RM range.
As a skinny guy already, how is high volume training such as we're talking about, going to help you get your goals? HIT (high intensity training) is as metabolicly stimulating as intense cardio, even more so with high reps, and low rest time between sets...your burning alot of calories and energy in the gym either way.. try to think of what applies to your bodytype, and your training history!
Alot of people who just started training and make intial great gains think they can keep training the same way and expect the same or similar results - this is NOT true of the vast majority of trainees. Gains will slow down and more advanced lifters will tell you that you must tailor your training to yourself, and the sooner you begin to find out what makes YOU tick, the better.