... another 'newer' MX author like me and infact we're going to be shelf buddies in the UK in November so be sure to grab both 'The Mile High Club' (Heidi's latest) and 'Bedded by Arrangement'...
In a nutshell, sex in MX is like sex in any other romance novel -- it's just another aspect of the characters emotional journey. However hot or not your sex scenes are (and that would depend on your voice, your characters, etc) it has to be relevant. Of course MX are looking for uber-sexy romances and I doubt if you'd get away with 'closing the bedroom door' so to speak. But 'sexy' to my mind is all about sexual tension and heat between the characters not mechanics. I've just finished reading Julie Cohen's All Work and No Play and that is one sexy, sexy book. If you want to know how to put enough heat on the page to burn it to a crisp while staying true to your characters that book's a great place to start. (And thanks a bunch Julie, now I'm going to have to overcome a long-standing prejudice and buy a copy of The Sun this Saturday for my free copy of Spirit Willing!)
The only other thing I'd say is have fun writing your sex scenes. I love writing them (and not just for the vicarious thrills). When your characters are making love they're at their most emotionally raw, their most exposed (both emotionally and physically). Think of all the great character development, conflict, tension, revelations etc you can build into those scenes and let rip I say.
All of this talk just makes me want to get my hands on the latest books by all these fab, fab, fab authors - don't you agree?!