Periodizing your training can help take your fitness level- to the next level. Periodizing involves manipulating training variables like reps, sets, and load on a weekly level in order to get the training adaptation that you would like. For example, if your goal is to increase muscular hypertrophy(growth), then each week you would want to increase your training volume(by either adding sets, reps, or increasing weight) until it’s time for you to de-load, and repeat the process all over again. Let’s say the first week you do 12 reps and 3 sets of bench press at 150 lbs; the following week you could either do 4 sets of 12 reps at the same 150 lbs, increase the weight to 155 or 160 lbs and try for 12 reps and 3 sets, or you could increase the weight to higher loads like 170 lbs and do 10 reps, but do 4 sets. The easiest way in my opinion to increase volume on each week is just adding one additional set. So, first week like I mentioned you do 10 reps, 3 sets, then the second week you could do 10 reps, 4 sets, and the third week you could do 10 reps, 5 sets, then you would de-load on that fourth week(decrease load by 40-60% and only perform a couple of sets). Taking a de-load week is critical because it will help you avoid overtraining and possibly developing injuries, and will re-synthesize your nervous system and muscles to handle even heavier weight the next time around. If your goal is to increase strength, then periodizing your training intensity (in terms of high vs. low loads) will be more important opposed to volume, but still an important factor when trying to develop strength.