Sexual Relationships 
Sexual Health 
I'd say it comes down to three things, the three 'R's.
No reservations
Sexual satisfaction for most women is much more mental and situational than physical. I would go as far as to say a lot of it is deeply instinctive. They want a guy to be above average. The females of all species want this, whether the male proves it by his very survival against the odds or by displaying some exceptional characteristic, no female wants an average or below average mate if she can possibly do better. When a woman is with a man who she can admire for some trait even if it's something trivial or seemingly unrelated to fitness her 'mating filter' relaxes. The more exceptional you are and in more ways the better but excelling in something is possible to almost everybody, so this need not be exclusive.
Excitement is one thing but ideally a woman needs to be comfortable as well. She needs to feel either that she is in charge or that she can trust the man if he is (if that's what she wants). That's not to say a frisson of danger isn't a pique to excitement but most women don't find actual fear sexually stimulating. Relief from fear maybe but not fear. The best way to make someone comfortable is to be comfortable yourself. Nervousness is contagious. Reassurances are good but they mean nothing if the atmosphere is fraught.
No resistance
By this I mean no physical problems. This is about technique and so much information is available I won't go into it. Basically just know where everything is and all the things that can possibly go wrong and head them off before they throw a spanner in the works. This is about making things smooth (or rough in a smooth way if that's what's called for). Read her, pay attention to every nuance. It's difficult to do this when you are excited yourself, like controlling a car and being aware of traffic at the same time but just like driving, with experience you will do it as second nature IF YOU PRACTICE. It will not come to you with simple repetition. You need to do it consciously first.
No regrets
Don't make her sorry she chose you. Don't lie or put on a false front or pretend you don't know what women expect. Unless a woman tells you up front she just wants sex assume she wants an exclusive relationship and the possibility at least, of a permanent one. If you aren't willing to give that a fair chance don't get involved. Let her know that sex changed things between you in a good way, that it made you closer. This doesn't mean you have to let her make unreasonable demands on you but you need to deflect such demands, if they come, in a way that lets her know she hasn't lost value by sleeping with you.
DON'T TALK, don't say anything to anybody about your experience with her. One day you may be able to discuss experiences in a general way, without names or specific details but nothing which could ever conceivably get back to or be associated by anybody with a particular person. Acknowledge the relationship openly when it comes up, don't give anybody any reason to think you are ashamed of it, quite the reverse, but no details, no assessment no rating.
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