Find your rep maxes for 15 reps, 10 reps, and 5 reps. Plan two weeks of lifting for each rep range. Start your first session at about 75 - 80% of your rep max, then increment the weights each workout. When you reach workout #6, you should be scheduled to lift your previously determined rep max for that rep range.
There may be some "zig-zag" in your weights as you move from one rep range to the next (e.g. 75% of your 10-rep max might well be less than 100% of your 15-rep max). Most of us just consider that "zig-zag" as a little blessing and a chance to let the CNS recoup a bit. Alternatively, you may adjust your weights to eliminate it.
When you finish your second 5-rep week and have hit your previously determined 5-rep max, you may proceed in any of several different ways. You could do another week or so of fives (that's what I've often done), either continuing to lift a your 5-rep max, or perhaps even incrementing the weight a bit. Or you could do some negative lifts (though this often requires a training partner). Or you could try doing a couple of weeks of triples. At this stage, everything is gravy.
When you finish your cycles, take a much deserved rest -- a Strategic Deconditioning. Don't exercise at all for 9 - 14 days. Sit around a lot and do nothing. Maybe watch some TV. Read a book. Get people to bring you things.
Then, when you hit the gym for your next cycle, even sub-maximal weights will kick your butt (and spur hypertrophy).