In life you can't always get what you want, but in bed—well, that's another story. Whether you want if faster, slower, more often, more intense, whether you have some secret desire to be painted in chocolate or tied to the bed board, chances are you can get your lover to oblige your desires.

But great sex—or the kind of sex you want to have—doesn't happen automatically or via telepathy or even intuition. You must be able to communicate your wants and needs to your partner, and therein lies the rub. Because if men and women have trouble communicating in daily life, imagine how tricky things get when you toss nakedness into the picture.

Luckily Ava Cadell, Ph.D., a clinical sexologist and author of The Stock Market Orgasm, is on hand to offer a few tips on communicating with your partner on what you want and don't want in bed. One of the biggest problems is that we all make love the way we want to be made love to, which is ridiculous, she says. "Men need more pressure (which causes them to exert more pressure when having sex) and women need less," says Cadell. So before even getting into the talking points of sex, Cadell recommends that men and women touch themselves in front of each other and watch how each pleasures him- or herself. "This can be very educational and very erotic," she says.

In addition to showing your partner what you like, you can also tell him or her. If, for example, you're having an intimate dinner that you think will likely end with you two romping away, quietly—don't want the maitre d' to hear you— say what you want him or her to do to you that night. Not only will doing this get both of your motors revved, but later that night someone will remember what you want and likely oblige you.

Sex life stuck in a rut? Then, timing, sensitivity, and tact are all paramount.

If you're tired of using the same old position, you must tell your partner. "You can complain, but don't blame," Cadell says. "However justified you might feel, it will only lead to resentment. Instead, give your partner a compliment first and then move on to what you'd like."

Here's an example: You're sick of doing it missionary style. First, look your partner in the eye and pay him or her a sexual compliment—"That sure was one mind-blowing orgasm you gave me last night"—which is a good lead-in to saying what you want: "Maybe next time we could try it standing up for a change." If you're delving into some real issues, be sensitive to when you bring these topics up. Complaints should come after sex. Men, for example, are at their most vulnerable in those five postcoital minutes, says Cadell. "For them, that's the best time to bring up 'touchy' subjects."

As for communicating what you want while you are in the midst of having sex, that requires a good bit of body language as well as some verbal cues. If your partner is giving you oral sex and you want your partner to concentrate on a specific area, you can gently move his or her head there. Or moan loudly when your partner's mouth strays in that direction; the point will be taken. "Verbally you could say something in a sexy, husky voice, like, 'I feel like I'm going to explode when you touch me there,'" says Cadell. Sex talk, as embarrassing as it can seem, can add an ultra-erotic dimension to the goings-on, Cadell explains. "It is to the ears what a mirror is to the eyes. It can turn a bad sex life into a sizzling one. If you're too shy to talk like a porn star, there are two erotic words everyone can say: your partner's name and yes—'Oh, Sam, yes!'"

Good sex talk is also detailed sex talk, which is important because you need to be really clear to your lover what you want. "You can't expect people to read your mind," Cadell says. "Be specific and spell it out for them. Meaning, don't just say, 'That feels good.' Rather, say, "When you move fast then slow like that, it sends me to another world."

And if things aren't going the way you want, don't give up and don't button up. Otherwise, warns Cadell, you could end up resenting the person. And even if you've already hit the resentment stage, hold the venom back. Nothing destroys an ego (and, thus, desire) like an insult to one's sexual prowess. Keep it in a positive light. If you don't like the way things are moving, fair enough. Say so, but always offer ways to make it better. Keep talking, and things will heat up before you can say, "Your place or mine?"