Your muscles WILL NOT get any bigger if you keep lifting the SAME amount of weight, Doing the SAME number of reps and/or sets each time you workout so for example...
Your chest muscles will not grow very much if you keep bench pressing 300 lbs. for 4 sets of 8 reps every Monday but...
If you tried to bench press more than 300 pounds, do more than 4 sets and/or do more than 8 reps on the bench press every Monday then you would start seeing your chest muscles get bigger and...
The only way for you to know if you are doing more and more each time you workout is if you keep a training log where you write down how much weight you used along with how many sets and reps you did so to build muscle fast you need to keep beating your last workout and/or set by pushing yourself more each time even if it's only by an inch
2. Don't workout If you can't beat your last workout.
If you ever end up using the same amount of weights, reps and sets for 2-to-3 muscle building workouts in a row then you need to take some time off to allow your muscles to rest long enough to get bigger and stronger for you to use more weight, do more reps and/or sets and If you're not getting stronger every time you workout then you're just wasting your time because you won't be able to workout with enough intensity to build muscle.
3. Don't use weights that are TOO light or TOO heavy
If you use weights that are too heavy then you'll just end up using bad technique and you'll end up working the weight instead of actually working your muscles and...
If you use weights that are too light then you will not be using enough intensity to build bigger muscles so...
You only want to use weights that are heavy enough to allow you to do the recommend number of reps so for example...
If you're supposed to do 5-to-10 reps on a set and you can do more than 10 reps then that does not count as a set because the weight you picked was too light and vice versa...
If you can't do more than 5 reps then that means the weight is too heavy so you need to either use lighter weights or...
You can do more reps (using good form) with a heavier weight by doing Drop sets, Rest-Pause reps or any other fast muscle building technique which will all make you have a much more intense workout to help you build muscle fast.
4. Make your muscles get bigger by eating right
Drink at least 1 liter of water a day because 70% of your muscles are made up of water so you need to drink water so... You'll have more energy to build muscle fast and your muscles will recover and grow faster and...
Eat more protein to build bigger muscles since 30% of your muscles are made up of protein you need to eat protein to repair and rebuild your muscles into bigger and stronger muscles after doing your muscle building workouts but this does not mean you should eat a High protein diet and as long as protein makes up 30-to-40% of your diet then you'll be eating plenty of protein to build muscle fast and...
Make sure you eat some fat so... Your body can make testosterone and other muscle building hormones and you want to make sure fat makes up at least 10-to-20% of your diet.