Arnoldwanabe probably should have given us a sample of his weekly workout program; how many day's, exercises, set's, etc. How much recovery time he allows between workouts, or during the week, can be very important..Something to give a general idea of his training. And in the last two years, did he make the most progress? I'm guessing about 80%-90% of guy's who seek advice here give none or a few bit's of information about training. Not much help when help is requested.
As Bluto suggested, target the larger muscle groups with heavy compound movements. And try to use free weights for most of your movements. Not that machines can not be rewarding, but the prime source should be free weight exercises like squats, Hack squats, DL's, SLDL's, Cleans,BB Rows, Chins (weighted), Presses, BP/IP/Dips, etc. These are the Big Boy exercises.
Training workouts should be brief and to the point. Done with serious intent with-in 45 to 60 minutes each session. As Smaul advised, eat more balance whole foods made up of good quality carbs. In simple terms, avoid white flour/sugar products. Don't know if you do or not, but you might want to include a Creatine produce and test the results they may give you. Make sure it have a delivery system includes, which is usually Dextrose/Beet Juice. I'm not a big fan of supplements in general. But I've worked with athletes (mainly football players) and have witness the mostly good results from taking this stuff. Also might include Flax Seed oil. Make sure the good quality calories are around 3,000 to 4,000 daily. You do not have to eat like a pig, just eat smart. If you find gaining excess fat, than cut the carbs a bit. Tweaking the body for max muscle gains really is not that hard if common sense is applied. Good Luck.