Fool around a lot before you go anywhere below the waist. Make sure you’re really wet (use lube if you want!).
Have him cut his nails BEFORE anything happens. Seriously.
It will be uncomfortable at first and he needs to do it gently. Your body needs time to adjust to the intrusion. So ask him to go slow, only ONE finger, and take it from there. If it hurts too much, stop and keep kissing, try again later, but he should gently ease into you when you’re really wet and slowly work up the pace.
Only do what you’re comfortable with. If you don’t like it, either stop him altogether or just ask him to do it differently. (Ie, slower, easier, whatever you need.) Don’t be nervous. You’re in control of the situation. You dictate the terms.
You will be sore after the first time, but you’re not going to experience PAIN. If it’s really hurting, then there’s something wrong with what he’s doing or you’re so nervous, you’re not letting your body relax and open up to him. Arousal is a huge factor here! The more aroused you are, the better it will feel.
So fool around, get comfortable, and let him touch you! 🙂