There are two different main ways and reasons to lift weights, and they are to either get buff or to get toned. Whichever solution you are looking for, there are plenty of tips out there for either method that can help you achieve the results you so desire.
A lot of women aren't looking to achieve large and bulky muscles by weight training. They simple want to gain tone and lose weight by adding an extra session to their daily or weekly training regiment. There are simple ways to do this, you just have to adjust the amount of weight you lift and the amount of sets you do, in addition to aerobic exercise. The key to toning your muscles is using a high amount of weight and lower rep sets. For example is your max bench press is 130 pounds, put around 90 pounds on the bar and complete 6-8 reps for three sets.
Men, on the other hand, are often looking to bulk up and add a lot of muscle mass, though this can apply to women as well. Strength training to bulk up involves lifting to exhaustion, or in other words, to the point where you cannot complete a single rep. This still involves heavy weights but at different sets. It's often recommended to increase the weight with each set and decrease repititions. For instance, with the same 130 lb max, you could start with a 8 rep set of 80lbs, then a 6 rep set of 95 lbs, and finish with a failure rep set at 110lbs.
For either intention, it is ideal to try to train each muscle group 1-2 times per week. So have a schedule laid out, such as legs one day, shoulders and back the next, and arms the third, followed by a rest or cardio day. Supplemental nutrition can also be essential in achieving your goals, whether they be protein shakes or bars, nutrient smoothies, or whey protein. All can help assist your muscles in growth and help them recover from your workouts.
So regardless of your reasons for going to the gym, they are many different ways to train. Some people train with cardio fitness only, but adding weight lifting to your regiment can be useful and very healthy for you in the long run. So consider adding a strength training routine to help you achieve your fitness goals.