Some great advice I can give you when lifting weights is, 'Form OVER weight'. How many of us are guilty of picking up the heavy weights, and letting our ego take over, probably just to prove something to the other guys in the gym. However, by doing this you fail to perform a good set and your form is terrible. I see it many times when I am working out and it can be very dangerous. By exercising this way you run the risk of injury, cause stretch marks and you could harm other gym members.
When lifting weights it's extremely important to make sure that you check your form before going heavy. By doing this you will condition your body to lift the right way, and be far less likely to injure yourself. Preventing injury is so important too. You may think that you won't get injured but I can tell you first hand that by performing exercises incorrectly, it will lead to imbalances and at some point something has got to give, which will be you unfortunately. By not using correct form and technique you could have imbalances within your body, which result in poor posture, aches and pains and other discomforts.
When in the gym it is crucial that you are concentrating on what you are lifting and create a connection between your mind and the muscles you are working on at that time. This is often a common mistake when lifting weights. Most will just be focused on lifting the weights up and down, or side to side with no real thought about why you are doing it. There needs to be a tempo within the set. You need to focus your mind on lifting the weight concentrically and eccentrically. By squeezing through the movement, this will also give you a better contraction between your muscles. For instance, when performing a bench press. This exercise primary muscle is the pectorals (chest). As soon as you take the weight of the bar, you should keep a moderate tempo. You should push the weight and lower it with control and squeeze the chest through each rep. This is great for hypertrophy type training (building muscle). However, if you are training for speed you may change the tempo slightly. By doing this you will initiate a greater pump with your muscles and target them more effectively. This is why looking into a mirror is great. When performing each exercise you can look in the mirror to make sure your form is correct.
Pay careful attention to performing the repetitions per set, per exercise. As you start to fatigue, you are more likely to forget about your mind-muscle connection, and just focus on getting the set done. In these cases, you then need to really watch out on your form, particularly when doing exercises where you can incorporate swaying or arching of your back. Avoid doing this, put the weights down and rest. For certain exercises , (bench press, bent over row etc) I realise it's very hard to look in the mirror to check your form, again, this is a point where it is handy to have a spotter with you who can do this.
So what can you do? Well, I propose you go back to the basics. Whether you are just starting out, or have been exercising for a while, start from the basics. Workout with someone who can check and make sure you are doing the exercises correctly. I also recommend you use a notebook, to record your weights, reps and sets you performed for that workout. By doing this you can keep track of your workouts, see progression and get fitter. It is far better to slow down, take your time, lift properly than to go in there with no plan and just lift. You want to stay injury free and achieve your goals, follow these simple tips and you will get there.