I recommend a good quality tri suit. I waited until my forth season to invest in one and regret it. If you feel you want to adopt this life style, the suit is a good investment, they are pricey but you get what you pay for. They should fit like pantyhose, very tight, they dry quick, don't creep and feel like a second skin. The compression also helps to support and stabilize muscles for the race.
By the way once you start you will get hooked - As far as injury goies listen to your body. Stretching is critical to healing and preventing injuries -
