You're over-thinking. Fuck her and be done with it. She will likely not do anything to make you eel embarrassed. You won't be much good the first time but she already knows that. Learn to slip two fingers into her vagina - palps upward - and then curl them in a 'come hither' motion, while gently rolling her clitoris with the ball of your thumb. Then, adjust based on the quality of her moans or lack thereof. It's best to conduct your tryst at a location well remote from family members, although having a quick standup in the greenhouse is not unheard of