Use Free Weights instead of Machines More Often

Machines will have its uses, but for a start, concentrate on free weights. That means work almost exclusively with barbells and dumb bells. Free weights recruit many stabilizing muscles for balance and control. That means you will work a lot more muscle parts other than the intended ones. That will give rise to little bumps, striations and definitions all over your body instead of one huge lump of muscle on your intended muscle. Because of the extra stimulant created, your muscles grow faster too. Why else do you think all professional body builders almost exclusively use free weights?
Compound Exercises Instead Of Isolation Exercises
Use as many compound exercises as possible to your workouts. Compound exercises are exercises that involve 2 or more joint movements. Because they utilize more joints, that means greater muscle mass are involved. Greater muscle mass means heavier weights. Heavier weights means greater muscle gain.
Some excellent compound exercises are the Squat, Deadlift, Chin ups, Dips, Bench press, Barbell Press, Lunges, Bent-Over Barbell Row…etc.
Train with Intensity 
You must train intensively like a mad man for your muscle to grow. Try to do more reps or add more weight than the previous session or your muscles will think, “Ah… we’ve done that. Nothing new, so no need to grow bigger and stronger.”
Because of this, it is important that every time you train hard, you give your body time to recover as it has suffered strains and actually sustained many small scarring. Your muscles grow when you rest, especially when you sleep and not in the gym. So sleep at least 8 hours a day. Also, do not train everyday or work the same muscle group more than once or twice a week. If your training was vigorous enough, do no more than an hour per session.
Try not to do cardio work on the same day as your weight lifting work. In fact, during the muscle building phase, you should do less cardio work as aerobic exercises burn muscles. You can increase your cardio work when we come to the cutting phase, to lose fats and gain rippling definition.
Correct Technique And Form
Everywhere, everyday, you will see people using wrong form and technique when training with weights. This not only compromises your growth, it will also make you susceptible to injuries.
Wrong form occurs usually when people try to lift weights that are too heavy, whether out of vanity or ignorance. As a guide, always lift with strict focus on the muscle you intend to build for that particular exercise. Feel it contract and extend. Lift the weights deliberately and slowly. Never ever swing your weights up especially when doing bicep curls or the military press. Lower the weights slowly, taking about 3 seconds instead of letting gravity pull the weight down. You must fight gravity to stimulate the muscles, if not, half of your effort is going to waste. Another common mistake is when people arch their back when they are doing their bench presses. By arching your back, you are using your spine to press the weight up. Your back must be pressed against the bench at all times for the exercise to be effectively working on your chest! However you MUST arch your back when doing squats and deadlift.
With some exceptions, as a general rule, if you can lift a weight in good form for more than 10 reps, it is too light. Conversely, if you can’t lift it more than 5 times in good form, it is too heavy.
To Grow Fast and Huge, You Must Perform Lower Body Exercises!
This is what most people don’t realize. Your lower body makes up 60-70% of your musculature. If you don’t train them, not only will you look spider-legged, your entire body will not grow as quickly and as large. Don’t think that you can hide those skinny legs in your pants! Most people do not train their legs because squats, dead lifts and lunges can be very grueling exercises. But it is precisely because of such intensity that you will produce more growth hormones when you sleep and overall muscular development is stimulated.
EAT and EAT Correctly
Losing weight and building muscles cannot happen at the same time although there are methods to do so and will be too technical to describe here. To lose weight, you must have a caloric deficit. To build muscles, you must have more calories, period! So do not be afraid to eat. Have plenty of protein, moderate complex carbs and some good oil like Omega, olive, flaxseed, fish etc., especially immediately after a workout. That is when your body is most nutrient hungry and will absorb whatever you eat very quickly. The longer you delay eating after a workout, the less effective it will be. Even better, take quick absorption protein shakes and high glycemic carbs during this time. The carbs will induce insulin production almost immediately and shuttle the protein to your muscle cells very quickly.
Eat about 2 gm of protein for each kg of your bodyweight or 1 gm per pound of your body weight. Spread your meals evenly throughout the day about 3 hours apart. It is advisable that you have supplementation of Creatine, Protein, Multivitamins and L-Glutamine.
Yes, you will probably gain weight, but a lot of it will be muscle weight because muscles are heavier than fats. You may also gain some fats because of the extra calories consumed. Don’t worry, it is a happy problem because the more muscles you have, the easier the fats are to shed when you come to the cutting up phase to get those rippling definitions. 
Easy isn’t it? Now that you know the facts, the rest is up to your determination. 

But remember to warm up and cool down, as well as stretching before and after each session; Or even better, after each set for better muscle recovery and prevention of injuries.