I agree with the breaststroke - my very first tri I swam on my swimming endurance alone without a whole lot of practice let alone in open water, and the adrenaline really got the best of me. There were so many people, it was all so new and exciting, I was overwhelmed. I breaststroked a lot more than I expected, though I did it fast and still managed to pass a lot of people. I didn't panic and the water temperature didn't really scare me, I just couldn't calm down into a race pace.

I would be prepared that you may panic a little bit, and that's okay - just take a few deep breaths and swim your own race. You can make it! You WANT to get through the swim so you can ride that sweet bike! Think about things in baby steps: reach the first buoy, swim 20 strokes, whatever it takes to just keep going.

Good luck!