I remember me. Always traying to change workout to find the best way to get bigger, faster, stronger and leaner at the time. I was bad. But now, I know what to do with my body to progress !

To get stronger, i usally use this method. Working great.

The way I do it, is to fix goals. For exemple, now on 16 feb 2013, I do 75 pounds 12 times at Incline DB press. My goal is to do 85 pounds 12 times on May. 
What will I do ?

Now I do 75 pounds 12 times, I will up the weight to 80. For exemple, I will do 7 or 8 times. I will do 4 set like this. The next workout I'll take the same weight push it and may be all the sets I'll do 8 times. The next one I'll do 8-9-9-8. And the other one 9-9-9-8 and after 10-9-9-9 and 10-10-9-9 and 10-11-9-9 and 10-10-10-10. and 11-11-11-11 and 12-12-12-12. Ok It will take around 8 to 10 workout of pec to pass of 8 to 12 reps for 4 sets. OK. For some it's long. But I do 8 workouts by months of all muscules. So in one month, I progress of 8 to 12 reps. So by the mid of march, if I do 75 pounds 12 times now, I'll probably do 80 pounds 10-12 times. Lets say 1rst april I do 80 pounds 12 times. Easy. So I'll go for 85 pounds and may be do 8 reps. And I'll go like this until the end of april, and do it 12 times !

So I'll got my goal. Ok 2 months, up 10 pounds DB incline, for the same number of reps. For me, that sound great. But How I'll do this? I track, every day, what I workout in my book. and with this, I'll see progression and motivates me. Thats'it. Slow, but still progression. 

To build muscle :

you have to work it men. Volume = muscle training = muscle pumping =  muscle contraction = YOU HAVE TO FEEL THE MUSCLE WORKING.

So drop the weight you use and take a weight that is high, to not too heavy, and work your muscle contract it and feel like this is the only thing that move. don't pay attention to the reps or weight, pay attention to your body working, to your muscle developping and to feel it hard. 

What I think is the best, you do a 2 warm up sets of 20-30 reps and really feel muscle with a low weight, around 50% of what you use. And after you go. May be if you do 4 exercises, do 2 warm up set, 1 exericse heavy, and others feel muscle so your not loosing strengh and you developp body. That'is it !