no expert here, but I did a Triathlon a few years back. Plan to do more, but my achilles has been acting up. Only advice I have is wear a wetsuit. Also, no one wears speedos. Spare yourself that humiliation. I didn't. It's really not that hard outside of swimming. So if you are prepared for that it is all really downhill after that.
Crap- Now I have to buy a different swim suit.
Somewhere in here I mentioned that I was in the CLYDESDALE div so speedos are not an option. The wife wouldnt let me out of the house. I have the spandex short to swim in and let me just say that they are not flattering. :no: