Different things seem to work for different people, so you'll get a lot of suggestions that may or may not work for you. Likewise, here's what worked for me. I'm sure it's not a guide of what to do, but it adds some color to what you've probably heard or read from others.
In three months (or less actually) I went from: (these are 5-rep numbers, not single pull maximums... I never bothered to test what my single pull max was on anything).
- 60 to 65kg bodyweight, 20 to 14% bodyfat (as measured with calipers)
- 45 to 70kg bench barbell press
- 40 to 80kg squat
- 60 to 100kg dead lift (no straps or powder)
My diet was healthy but not high protein.
I never slept properly... rarely more than 7 hours a night; but I did take 2-3 days between workouts. I went to the gym 2-3 times per week.
I did almost exclusively just the big three - squats, dead lift, and bench press: squats and bench one day, then deads and bench the next visit. Each exercise was one warmup set of 10 reps, then 5 sets of 5 reps - increasing the weight by small or large amounts depending on how I felt on each previous set. My final set would be at my highest weight, and in some cases I could jump straight from the warmup weight set to the heavy weight set immediately.
I took no supplements.
Since I'm not predisposed to big muscles, I guess the specific workouts plus the ample time between workouts contributed to my success.
Then I plateaued and stayed at those numbers for a LONG time. But since I don't need to get bigger or much stronger, I'm shifting my goals to endurance and general fitness.
As a side note, the big three help you create a really strong core, without crunches! Yay.