Q: How to know before commitment, the person you are interested in, is sexually compatible to you?
A: Skip the outdated advice, and go ahead, and ask these important questions, before anything gets serious. Otherwise you are going into relationship completely blind.
1. Ask not only from the other, but also yourself: how important intimacy and passion are to me? How about my appetite?
2. How about the attitudes towards the use of contraception? Are lovemaking and intercourse synonymous to you? Is intimacy for procreation only, not for pleasure?
3. Things you would not compromise on! Do they know what climax is? Do they use movies or other material? Maybe they like one position only, or hate the idea of oral pleasure?
4. What are the things, they don´t like at the moment? How open they are to go with the flow? Or they have the need to be in control all the time? How open they are to experiment new things?
Big differences in preferences most likely tear relationship apart. However, intimacy gets better by the time, as the couple gets more comfortable with each other.
If you have similar attitudes towards intimacy, enough attraction and appetite, compatibility will naturally fall into place, when both are curious, willing to learn and most importantly, ready to teach each other. And finally to communicate, what feels good and what not.
If you are still too shy to ask directly, that is a sign, that you are maybe not ready for an intimate relationship.