Oh, if you want to continue climbing regularly the tips above can help.
But for your first time rock climbing, take it slow and steady, but also keep in mind that the longer you hang around the more tired you can get. If you're tired half way up the wall or if you can't get to the next grip just communicate to your belay partner that you want to come down.
Your friend will give you tips and can point out footholds and technique while you are climbing. There's really not much way to prepare for your first time climbing other than keeping fingernails and toenails super short and listening to what your spotter/belay and the climbing guides have to say.