Form, function and volume.
Proper form is important, but too often it's an excuse. If you aren't bouncing a bar off your chest, bouncing at the bottom of a squat, or doing stupid shoulder exercises that directly damage your shoulder, don't be afraid of a little momentum. Besides, there is no such thing as perfect form, simply because no two people are physiologically identical, so there is no way to reproduce another's form. The key is to not endanger yourself by doing something stupid, don't use 'strict form' as an excuse for not lifting heavier.
Some good sources of training info:
"Dinosaur Training" by Brooks Kubik
"Science and Practice of Strength Training" by Vladimir Zatsiorsky. This one is pretty technical and intense.
It's not rocket science that lifting heavier weights will recruit more muscle fiber, which will lead to more effective results. Heavier weights = more strength = more effective workouts. Simple. Now the tricky part: utilizing the biggest muscles results in more strength in those muscles... AND more testosterone
. More test = more strength = more weight = more results.
Here's where the new/hardheaded guy comes in: "But I just want bigger arms." Without increasing hormonal response in the most efficient way (lifting heavy with the larger muscle groups) you're not giving the body any impetus to grow. Secondly, it's virtually impossible to isolate a muscle, no matter how hard you focus on concentration curls or preacher curls, your biceps aren't the only thing working. Since that's the case, pick up the heaviest barbell you can curl, and curl it. If your options are rocking your body some, or not lifting heavy weight, rock.
Side note: if you can't do at least 10 chinups, don't mess with pullups. And pull from your armpit, it'll help you focus on activating your lats.
Low weight, high reps for fat loss: I don't know why, but this concept drives me nuts. I tried it years ago to 'tone up,' realized it didn't work, but never had any proof. Now I do: http://www.ncbi.nlm.nih.gov/pubmed/11932584
. This study was conducted on a group of women, who, as we all know, naturally carry more fat and less muscle than males. There are many other reputable studies showing the same results, but I prefer the one using females as an example, simply because if it works for their physiology, it'll work for a guy.
Basically it says this: lifting heavier percentages of your max for a lower number of reps increases the load on your oxygen consumption compared to higher reps with a lower percentage. What's that mean? It means that lifting heavy essentially is another form of cardio. So not only are you getting stronger, you're priming your body to boost it's metabolism. Just an added caveat, muscle burns more calories than fat, even when not working.
If you want to get big, hypertrophy is your goal. There are a couple ways to achieve hypertrophy, and they both involve a high workload.
Method #1: Body builder style set-rep ranges, focusing on specific areas of the body with 3-4 exercises per body part, for 3-5 sets, rep ranges varying from 5-12 depending on the lifter's specific goal in that workout, and a shit ton of other factors. Body builder routines are not pulled straight from the pages of a magazine, but are the result of that lifter's years and years of work, and his determination of what works for him.
Method #2: Powerlifter/strongman/olympic style work, more focused on a specific movement or event, with up to 10+ sets per exercise, with rep ranges from 5 reps down to singles. Lots of techniques that would be considered odd in your average gym are utilized, like bands, chains, boards, boxes, bumper plates and all kinds of other fun stuff.
Both methods work, the results differ in many subtle ways, but the key thing is lots and lots of lifting at high intensity, no matter what the rep range.
Recovery & overtraining:
Gains are made in the kitchen, in bed (in more than one manner) and with active recovery. Stretching, massages and foam rollers are all tools that increase the rate of recovery, allowing more frequent, intense workouts. If you're too sore, you can't get an effective workout, so work on getting rid of soreness.
Overtraining, theoretically, doesn't exist. What is true, is that you are capable of stressing your body to the point where you can't recover in an efficient manner. It's been said many times, that over training is just under sleeping and under eating. What it all means is that there is a balance to be found between work load, exercise load, dietary means, and sleep. Over training is talked about as if it'll make you weak and cause your muscles to shrink, which is bullshit. If you can take a week off and be back to the grind, then it wasn't over training, it was under recovering.