You could go with a traditional method, like a candlelit dinner at home, romantic music, and with you wearing something slinky and sultry. All of that stuff really does work, because it sends out all of the signals that you're making an effort to really be exciting and sexy for him. But you need to back up that stuff with the right frame of mind. You don't need to wait for a special occasion to be more sexy for your man, just choose a time that you feel comfortable with. If he's the kind of guy who likes schedules, feel free to plan it in advance so that you can both relax more.
Make it special. Light some candles, wear something that makes you feel red hot.
You might think that having a romantic night with your lover seems a bit silly, especially if you've been together a long time, but don't underestimate it. Guys like to be made to feel special, too. And when one person does that for their partner -- the partner will be more likely to reciprocate sometime down the line.
Remember that confidence is key. Many confident women are brought up being made to feel as though they are beautiful, competent, and all-around wonderful. As they grow into women, this confidence translates into greater professional successes, as well as personal ones.