In a previous iteration of this blog, I had a post about understanding your gear. I feel like it needed to return to this iteration, as it was one of the best posts in the old version.
One of the first things I do when I get new equipment is to take just the new gear and whatever else I need to make the photo (ie, if I get a new lens, I take only the new lens and the body) and head to a familiar place. When I lived in Virginia, I used to go to Manassas National Battlefield Park and walk around one of the trails. I knew that trail very well, so it was a good spot to test out new equipment.
The reason to go to a familiar place is for just that reason, it is familiar. I knew that at mile marker 2 there was a nice clearing with an open field and some trees. About 20 minutes later there was a small stream (Bull Run) and a stone bridge. There were always surprises, like wildflowers in the spring, and deer just about all year.
So my suggestion is this — when you get something new, and before you take it out on that really nice trip to the exotic location, take it to a park near where you live, and do this for all of your gear. Just taking it on that first trip will help you get comfortable with the gear and make you more relaxed during the time it really matters.