My first time out was nerve wracking from the standpoint of getting ready and driving to the place where we were to meet. Once I had parked the car I had a moment of sheer panic where I seriously thought about just driving back home. After I dithered for awhile the thought came to me - "Do you wanna do this or not?" and the answer was "yes". So I took a deep breath, opened the car door, and embarked on my maiden voyage in public as me.
And you know what happened? Nothing. Absolutely nothing. No one paid me a bit of attention, no one made snide comments, no one beat me up. After my friends and I sat in the bar for about 30 minutes talking I completely forgot about being dressed as a female with makeup on in public and was just enjoying the experience of being ME.
My suggestion is to try to relax and not worry about every little thing and just be YOU! You will be among friends that will help you as needed, and you will be fine!