Gaining strength in the gym takes an extreme amount of work and can take months to even put an extra 20 lbs on your lift. Adding an extra 20 lbs to your max takes consistency and a high protein diet. When you are training for strength, a high protein diet is essential. You need to be consuming at least your body weight (lbs) in protein (g). When consuming that much protein, your body uses what it needs, and your body converts the leftover into carbohydrates, which the body then uses for extra energy. So yes, in order to get stronger you will usually pack on a few pounds.
Another necessary variable for gaining strength is your intensity in the weight room. By intensity, I mean how much weight you are training with. You need to be going up to 85-95% of your 1 rep max. Doing 5 sets of 5 has been proven to be a very efficient way to gain strength. Do a couple warm-up sets with a light to medium weight, and begin your working sets. Start with 65-75% of your max and work your way up to your max with 5 reps. Doing an occasional 1 rep max is perfect for tracking your progress and believe it or not it actually does help with strength gains. Staying consistent with this routine with no doubt make you stronger. It’s easy to get discouraged when training for strength, just remember to warm up properly before each lift to make sure your muscles are ready to go.
There has been rumors that static stretching can actually negatively affect your strength before a lift, but it has not been proven. I personally stay away from static stretching before strength training, but I always make sure to stretch immediately after. I also have noticed that I am able to lift more weight when I warm up for 20 minutes or more. My warm-ups usually include dynamic stretching, light weight warm-up sets, and 5-10 minutes on the stationary bike just to get the heart pumping for better blood flow.