It's the simplest thing, and yet so few of us do it.
I'm talking, of course, about asking for what you want in bed. This is something gay couples tend to be particularly good at, mainly because gay sex tends to necessitate a bit more negotiation - eg: "Are you a top or a bottom?", "Do you prefer penetration or no penetration?", "How do you feel about strap-ons?", etc.
Unfortunately, in the world of hetero sex, we're basically taught that the conversation around sex begins and ends after the green light is given to begin getting it on.
I've had women ask me "How do I give a good blow job?" and when I respond by asking them "Well, what does your partner say he likes?" they almost always answer with "Oh, I've never asked him. I'd feel weird about it." Isn't that in and of itself a weird concept? The fact that you'd happily put someone's DICK in your MOUTH, but then feel "too weird" to simply ask what BJ style they're into?
Unfortunately, our sex-negative culture has made us believe that talking about sex - even when we are literally in the middle of the act itself - is dirty and wrong. It's a pervasive and highly problematic myth that is leading most of us to have vastly unfulfilling sex lives. After all, if we don't communicate during sex, how can we possibly satisfy one another? Unless you possess mind-reading powers, that's going to be an impossible challenge.
I'm not just talking about sex in long term relationships here, either. I'm talking about casual sex too. Casual sex may even be more important when it comes to communication because the other person often doesn't know us well enough to have any idea of what we're into in bed.
If you don't know what you want yet, that's okay. But you need to go find out. Porn and masturbation are two great ways of exploring that. Then report back to your partner with what you need and DON'T let the communication end there. Keep it open during sex itself. It personally took me a few discussions before my boyfriend was able to do exactly what I wanted in bed - had we not kept the conversation open during sex, we never would have gotten there.
You have a right to have the kind of sex you want. Stop letting fear and shame hold you back from having the sex life you deserve.*