I can only suggest applying my specific requirements. Trust and comfort. It starts upstairs, first. A cerebral connection of trust and comfort between myself and a gal are what only begins the journey or at least only feels like it's the right way. You probably have a completely different level of trust and comfort, but I think this "formula" is a pretty good one. It allows the feelings that I want, anyway. I think it has to allow for the worries of experience to go away and just learn and enjoy one another.
Also, the main thing about this process is that you end where you begin. Sex as a physical act in a real relationship (at least as I have known it) is not the bulk of the time you spend together. You better have trust and comfort in all other aspects, or your get together will just be a fling and leave you feeling hollow, confused and frustrated. Then the other definition of "experience" is all you are left with - it was an experience, and you may regret that you don't have it again or have the chance to redeem yourself, if that is what you feel kind of bothering you.