Your first portrait shoot and you are jumping right into nude/semi-nude?
Part of getting good portraits is creating a comfortable atmosphere. That may mean taking your time and maybe taking a lot of shots. The model (and you) may be nervous or uptight at the start but with the right atmosphere...you will both loosen up and be able to create better results.
For this reason, it might be a good idea to start with a clothed shoot and do the nude stuff when you are both more comfortable. (or jump right in if it's going well).
These are things that may be different for every photographer on every shoot. Not something we can just suggest to you...not without more info anyway. We could say to shoot on the beach in Hawaii, or up in Machu Picchu...but that may not be practical.