One of my favorite sayings is to work smarter not harder. When you take the time and effort to lift weights, you want to get the maximum benefit from your efforts. We’re always being told what we should be doing at the gym: go faster, harder, slower; use a medicine ball; buy a band; free weights; body weight! But more important are the things we shouldn’t do during a workout. I am a little obsessive about form, and I see some crazy stuff going on in the gym each day. When is the last time you paid close attention to your weight lifting form?

So that you don’t cheat yourself out of an optimal workout—here are some common mistakes and solutions.

MISTAKE 1 : Skipping the warm-up. If you are lifting significant weight and you don’t warm up, it will be harder for you to lift because your muscles won’t be ready. You will also increase your chance of injury.

Solution: Do a general warm up before you start lifting, by using a cardio machine at a moderate level for at least four or five minutes. Then do a specific warm up for each of the exercises, starting with about 10 reps of 25% of the weight you intend to lift, and then moving to 50%, before you do your real workout. So, for example, if you are going to do 10 80-pound squats, start by doing 10 squats using just your body weight, and then 10 more squats using just the bar. Then go to your workout (three sets of 8 to 12 reps).

MISTAKE 2 : Stopping short. Not exercising through a full range of motion is a common mistake, especially when doing biceps curls. Many people stop the exercise before they’ve extended their arm all the way down. This means they are only strengthening the upper part of the biceps instead of fully developing the muscle.

Solution: Each exercise should be done in a slow, controlled manner through the complete range, with emphasis on the completely contracted position. Full-range of motion movements contract and strengthen the muscle you’re working and stretch the opposing muscle (in the case of the biceps curl, the triceps). Note: Do not confuse full range of motion with hyper extension—when you use more than the full range of motion, which can cause joint injury. Hang your arms by your side and relax them. This is your range of motion for the biceps curl; anything more and you’re hyper extending. Unfortunately it’s easy to go too far if you aren’t careful. You are in danger of hyper extension any time you use any type of free weight. That’s why it’s so important that your movement is controlled, and you use the correct amount of weight.

MISTAKE 3: Holding your breath during a lift. It’s easy to forget to breathe. My trainer had to remind me constantly to breath. Lifting weights causes your blood pressure to increase temporarily; holding your breath makes it soar even more, and then suddenly drop. Such a dramatic fluctuation in your blood pressure can make you pass out.

Solution: It’s important to develop a breathing pattern while you’re lifting. Some people inhale at the beginning of a repetition and expire at the end, others inhale on the upstroke and exhale on the down stroke. It doesn’t matter which you do. The point is to take a breath with each repetition to make sure you’re not holding your breath.

 MISTAKE 4 : Lifting hips off the seat or bench when doing exercises. For example  when doing a bench press. When you lift your hips you change the angle of your shoulders as you lift the bar, so you are using only your lower pectoral muscles instead of the entire pectoral muscle. Your feet are also contributing to the movement, so you’re not working as hard. More importantly, this also puts more of a strain on the spine which can lead to injury.

Solution: One simple way to prevent this is to place your legs on the bench with your knees bent and your feet down. How does this stop you from making that arch? If you are tempted to push with your feet, you’ll find very quickly that you’ll lose your balance and fall.

MISTAKE 5 : Straining the neck when doing crunches. Straining the neck is a very common mistake with crunches, because people place their hands behind their neck and then yank their arms to bring their head up rather than using their abs.

Solution: Do not do the crunch with your hand behind your back. Instead, cross your arms in front of your chest and hold your torso, neck and head in strict alignment. Your back will elevate to the lumbar spine region, which is exactly what you want. Lifting your torso (and not just your shoulders) off the floor will give you a lower abdomen workout as well. You can also vary this by adding oblique twists.

MISTAKE 6 : Rocking hips and pelvis while doing biceps curls. If you’re moving your pelvis back and forth during biceps curls, you are using the momentum to help you thrust the dumbbell upward, rather than isolating the muscle and using it to lift the weight. You aren’t getting an effective workout, and you can also throw out your lower back from the back and forth motion.

Solution: To make sure you perform the motion allowing only the biceps to contribute to moving the bar, try the exercise seated, with your legs spread, and rest your right elbow against the inside of your right leg. Then do the same on the left side. Another option is to use a preacher bench, or to stand up against a wall with your butt and back firm against the wall. You should have a 25-degree hip angle, with your legs straight.

MISTAKE 7 : Being wimpy with weights. If a weight is so heavy that you have to jerk, bounce or swing to get it to the top of the movement, it’s too heavy. But on the other hand, if you can do 20 or 30 reps your resistance is to light, and you are wasting your time. You’re not getting enough resistance training to increase muscular endurance or muscle size.

Solution: The setting should be chosen so that your muscle fatigues by the last repetition on the number you choose to do. For example, if you do sets of 12 reps, the 11th and 12th rep should be a struggle, after which you need to rest 1-3 minutes before you can do another set of 12. This takes a little playing around to determine the initial weight. When you are able to do 15 reps at that weight, it’s time to increase the weight.