man there are plenty of different schools of thought on this. i'm by no means an expert, but i've read a lot about it.
imo... the strategy that makes the most sense to me (based on science, studies, empirical evidence, etc.) is to use the HCG just prior to the clomid. there was a great post explaining the science behind this reasoning. The short version goes like this: Clomid helps your nuts get back to pumping out testosterone. But HCG helps regenerate lost testicular mass. Therefore, use the HCG to regain testicular mass, THEN use the clomid to get your now full-sized gonads functioning properly.
With the long half-life of deca, you would probably want to start using HCG right after your last shot. I'm not sure about the dosage or schedule, but it would probably work to run the HCG for the three weeks immediately post cycle, then start the clomid therapy at 3 weeks post cycle.