2. Use Free Weights. You can lift the heaviest weights using barbells. More weight is more stress, thus more muscle. Dumbbells are great for assistance exercises, but not for your main lifts. Stay away from machines.
Safe. Machines force you into fixed, unnatural movement patterns which can cause injuries. Free weights replicate natural motions.
Efficient. Free weights force you to control and balance the weight. This builds more muscle than machines, which balance the weight for you.
Functional. Strength built on machines doesn't transfer to free weights or real life. No machine balances the weight for you in real life.
Versatile. You can do hundreds of exercises with just 1 barbell. Saves a lot of money and space, especially if you want to build a home gym.
3. Do Compound Exercises. Isolation exercises are ok once you've built base strength & muscle mass. But if you're starting to build muscle, exercises that hit several muscles at the same time are better.
No endless Biceps Curls -> Pull-ups, Chin-ups & Barbell Rows
Also no Triceps Kickbacks -> Bench Press, Overhead Press, Dips
And definitely no Leg Extensions -> Squats & Deadlifts