As LL alluded to, varying the weights and rep schemes will get you the best results. There's some evidence that suggests that sets in the range of 8-12 reps are the best for building muscle, but the studies ignored the effects of adaptation. You do need to mix it up a bit. I go through phases where I do sets of 5 reps at higher weight, phases where I go to failure (very taxing), and phases where I go with lighter weight for more reps.
But one of the best things is to progress the resistance AND reps in what's called "double progression." What you do is this: Pick a rep range that you want to stay in. Pick a weight that will allow you to do a number of reps toward the lower end of your selected range, and stay at that weight doing as many reps as you can. Over time, the number of reps you can do will increase. When you get to the upper end of your rep range, up the weight to where you're at the low end of your rep range again.
One BIG caveat: I'd be very cautious about taking movements like squats or deadlifts to failure -- the potential for injury is too great to go to total failure, as form will break down before you get to that point.
Also -- do some warm-up sets in each movement before going to your working weight. Example: When I'm doing squats, I'll start with a weight that is at most half of what I'll be doing for my main work sets. I do this to warm up the muscles that I'll be working, and to make sure my form is totally on track. I'll do two more sets, progressing in weight toward my work weight. Then I'll do three sets at my work weight.