You will undoubtedly be nervous, so to counteract that, focus on hitting everything cross court. It gives you the largest margin for error.
Don't focus on hitting winners, just stay steady and hit cross court. If you get a short ball, don't try to hit a winner. Hit a sensible approach shot towards a corner, slice it if you have to.
At your level it's all about getting the ball back and being steady.
Have fun, let us know how it goes.