I was and am an ecto if there ever was one. I've learned that I need to eat like a monster to grow. Making homemade weight gainers (oats, PB, olive oil, whey...etc) are a great addition.
I don't think adopting different workouts is really neccessary, but I wouldnt do a lot of isolation exercises. Squats, deadlifts, bench, and chin ups should be the base of your routine. Eat a lot of low gi carbs, and a lot of protein and get growing!