its very easy to increase ur strength, atleast for me it has been the case.
for this u hv to workout the target muscle, with much heavier weight, which can fail u in 5-6 reps. strt with light weight to get the feel of the excercise and warm up ur target muscle. do 1 or 2 sets with this weight. then in the nxt set, go for the weight which u feel, cant lift for more than 6 reps. nxt set, u shld try to lift weight which can fail u in 4 reps, and the nxt one shld fail u in 2 reps. these numbers can b twisted a bit, but take care to fail u below 8 reps. u may also try to cut down the rest period between the sets, but tht may put too much of load, so use it if u feel u can afford it. do 3 or 4 types of excercises. in the similar way. attact the same muscle next day also. the trick is to not to give ur muscle much time to grow up, so to cope up with such heavy weights, it has only option to grow stronger. u may also workout the same muscle 3rd day also, but it may b risky. better wud b if u give it rest on 3rd day and again attack it similarly on 4th and 5th day. within a month, ur muscles will b much harder and stronger. try out this strategy and if u dont feel, it has worked out for u, do let me know.

PS: Do try to increase the weight u r lifting after every 2 workouts.

Country India