Does swimming in cold water fill you with dread?  Coach Justin Granger has some great tips.

Dealing with cold water swims is different for each and everyone. Some cope better than others and more often than not experience is a big factor in better dealing with it.

The best preparation is to practice in water temperatures similar to what you will experience on race day. Benefits to this can be achieved even as close as a few days before. This practice will teach you how best to learn to deal with the shock that the body will encounter.

Check out Triathlon training plans from Justin here.

Other than practice, my tips are to perform an extensive (20mins) dry land warm up, like running as close as possible to race start time as allows. Even overdress for this to really heat up your core temperature and have a good sweat. Try to maintain this elevated core temp up until the race start.
I suggest that if the water is near or below 60f don’t even get into the water prior to the start, as your core temp will drop and you will start to shiver. Just keep warm by moving around in your wetsuit even keep a beanie, gloves and thick socks on and dump them just before the start.

Before the start try to keep calm and focus on your breathing, take long and controlled breaths. Be prepared for the tightening of your chest and a shortness of breath that will follow a few strokes after the gun goes off. Make a concerted effort to not sprint too hard off the start and build your pace gradually as you adapt to the cold water. If you need to get more air in don’t stop, but rather start to Brest stroke with your head above water, then resume swimming as soon as you are ready.
Think about getting a neoprene hood if you have concerns or even 2 silicon caps can provide more protection.