If you are worried about getting it in her eyes and nose, stick to shooting perpendicular to her face. Have her lay down on her back and shoot across her face from the side, like side of the bed or couch. Stick to the bottom half of her face or shoot towards her chin. Mouth open or closed as she prefers. At least until you guys get more confident.
Tell her to keep her eyes closed. Have a wet, warm rag either ready or get one quickly in case she get overwhelmed. Listen and look out for signs she isn't comfortable. A cooperative facial is best, hopefully she gets more comfortable and you guys can have many great facials.
About the eyes, I have read that if you use the eye drop gel, it can help with cum in the eyes. But you have to use it before you get it in her eyes, it wont get it out.
Good luck!