If using a 5 x 5 routine, or just to build power in a single exercise,I think it`s best to start a bit below maximum poundages (quite a bit actually),then once you can complete all 5 sets of 5 reps with a certain weight,add just a 2 1/2 pound plate to each side at the next workout, and go for it again..............repea t,again adding weight when all 5 sets of 5 reps are met.
Small increments, and starting out lighter at the beginning, will see you add quite a bit of weight to an exercise over time.