Count your workout reps backwards. When you are at the end of a set, you will think about how many you have left to do instead of how many you've finished.
During a lat pull down instead of putting your thumb around the bar, place it on top beside your index finger. This will decrease the involvement of arm muscles, and focus on strengthening the back muscles.
Use dumbbells, barbells, and machines in that order. Stabilizer muscles fatigue from dumbbells before your larger muscle groups do, making your smaller muscles need less help as you progress to machines.
It may seem pretty straight forward, but it's often over-looked; when trying to build muscle one of the most important things is consuming enough calories to fuel both your exercise and the metabolic processes needed to build muscle.
When weight training it is imperative that you give your muscle tissue a chance to repair itself. During lifting you are actually tearing muscle fibers and each time they repair themselves they become stronger, but they can only recover during periods of rest.
The best rep range for gaining muscle size is between eight and 20 and at a weight that is between 60% and 80% of what you could lift for one and only one rep.
Keep a training or workout journal. Write down what types of exercises you're doing, how many reps at what weight, what time of day you workout, how you felt about the workout, and anything else you can think of. This will allow you to see what types of exercises work for you, as well as your progress.
Next time you're lifting weights try sitting on an exercise ball rather than a weight bench. Doing this will improve your core stability by working your abdominal and stabilizer muscles at the same time as strengthening the muscles you are targeting by lifting.
Do your cardio workout AFTER your weight workout. Your muscles need glycogen for the high-intensity weight lifting, if you do cardio first you will use it up and have little left for your muscles during lifting.
If you are weight training, trying to put on muscle and your body refuses to grow, take a minute to think about whether you are over-training it. If the answer is yes or even maybe, adjust your training and back off.