First, let me tell you up front, this is a man writing this. I'm also not thinking about any clinical issues when I answer. I hope that some ladies will respond to this, too. I am writing from my experience with my wife. We've had our dry spells, but we've also had our fantastic times. The first thing I've learned in this is to really get to know the lady because, even though there may be some tendencies we point out, every one is going to be an individual.
So some ideas on what I think, and what has worked well will follow. Honestly, I would like some of the ladies on the site to critique what I tell you for my benefit as well as the benfit of this discussion.
1. It can't start 5 minutes before you want sex. Most times, she needs to feel genuinely loved and secure. Doing your part to make her load lighter is almost always appreciated and remembered.
2. My wife loves for me to do things just for her such as massaging her feet and legs, or maybe even more of her body. I actually do this most evenings for her, and I never attach any strings - it is just for her. Take some time and plan it out so that she knows it is just for her. By this, I mean learn how to give a good foot massage if that's what you're going to do - look it up or watch youtube videos on it. Find what kinds of lotions/oils she likes and go buy them yourself. Maybe even present it to her gift wrapped. Make sure it's not just a quick trick to seduce her.
3. Sometimes, I will paint her toenails just before I massage her feet. Again, no strings attached - this is just for her. Maybe this should be the same subject as #2. On both, when I say "No strings attached," I really mean it. It doesn't require sex afterwards or any favors. Sex doesn't always happen that day, but she remembers such things when a good moment for her arises, and when she remembers, her heart is really in it.
4. Find what her fantasies or fetishes are and listen with understanding. Indulge her if you can. I've found that women (even my wife) sometimes fantasize about things that may make you uncomfortable as a husband - things like fantasizing that you rent her out to a rich man for a night for some exhorbitant amount of money. When my wife tells me about these kinds of fantasies, I will listen and understand her humanity. She really doesn't want this, but she likes to fantasize about it. I tell her that in the real world, I'm not going to share her with anybody, but in the fantasy world, I'll help her act out or roleplay any of her fantasies. I'm sure there are differences between ladies, but my wife loves the security, and the fun of that response and follow through. On fetishes, it may put you needing to do something that makes you very uncomfortable at least at first. I've just discovered my wife's kinky little fetish after 27 years of marriage (described in another post) and it embarassed me at first to do it for her - at least when I just got started, it became nice before it was over. However; this has thus far resulted in some wild nights as it turns her on like nothing else I've ever found. See if you can get your lady to really communicate to you if she has such a fetish, and see if you can indulge her if at all possible.
5. Don't make it all about the time you spend in sex. Make sure you take the time to cuddle and talk afterwards and take care of the emotions along with that. For me, I found that the number one reason for our dry spells was that I stayed up late at night writing or studying (I don't need much sleep) while she went to bed. She needed me to go to bed with her and just hug her, or let her hug me while she fell asleep on nights when there was no sex involved. When I neglected that emotional need, she was not in the mood much. I suppose that is understandable. So I would say find what her emotional needs are and be sure you meet those. (Another place where I need to be sure my lady's emotional needs are taken care of: I brag on her to my friends, and even better, I brag about her to her friends when she is there to hear it. I don't make it embarassing for her, and I make sure it is genuine - something I can honestly brag on her about and she knows it's honest.)
6. Sometimes, you just ask. She might actually be waiting for that.
When I think about our lovemaking, I would categorize our sessions in 3 ways: Romantic sex; Wild sex; and quickie. For the quickie, we don't have much time, and it is usually initiated by me asking straight out. Romantic sex happens when I am sure I am taking care of her and she really feels loved. Sometimes she initiates it, and sometimes I initiate it and find she was really waiting for me to initiate it. Wild sex is hard to predict, except when I've indulged her in her fetish, and she's had time to think about it, so usually the night after I've indulged her (although some of her fantasies can be called "wild."
Personally, I like having the balance of the three, but if I had to give up two and have only one, I would keep the romantic sex. You might have noticed that in my response, but maybe I'm not so different from other husbands in that.