Technique is extremely important in swimming. My coach used to say that swimming was 80% efficiency and 20% effort. For two people of equal strength, the one with better technique will come out on top every time.
Tip 1: Swim fast in practice
A note about wetsuits: Most triathlons allow racers to wear wetsuits if the water temp is below 78 degrees – which is what you will often encounter. Wetsuits not only keep you warmer in cold water, but they help with your buoyancy and body positioning while swimming. For longer races, they can help reduce fatigue too.
Be sure that the wetsuit you are considering is one that is made for triathlon (like these). Some wetsuits are made for surfing or other ocean activities, and they do not have the design or construction to be comfortable for a competitive swimmer doing swim strokes. Also, be sure you practice a few times in your wetsuit before race day. They feel a little different, and you will want to get used to not only swimming with the wetsuit, but also putting it on and taking it off (which requires a little practice).
Removing the wetsuit will add additional time to your Transition 1, but in most cases it can be worth it.