I've written a lot of sex books over the years and given a lot of advice. Most of it, I still stand by 20 years on.
But there's been an enormous amount of research into sex since I started out and we understand more about our sexual systems and responses now, than we ever have. This means original theories need to be reconsidered - and maybe completely rethought.
The following sex advice is doled out over and over again, year in, year out.
What's stood the test of time and what's actually a load of rubbish?
What sex advice has stood the test of time and what's actually a load of rubbish?
Sexy lingerie will revamp a tired sex life
Can new underwear really sort your sex problems? It's not going to solve the serious stuff but if you've just fallen into the been-together-forever rut, it can help because it shows what's really missing: effort.
Does he really need to see you in those big, grey pants? This advice has stuck because there is truth in it - it helps to look as good as you can, for your partner to fancy you.
You should talk about sex
No-one baulks at taking this advice when their sex life is good, it's only when it's bad that people object to it. In the beginning, you can't shut up about sex – if you're not talking about what you're getting up to already, you're talking about what you'd like to. Until something goes wrong, then it's not quite so much fun.
And just when you really need to be talking about sex - when there's a problem – you both suddenly clam up. Research has proved this one 100% accurate time and time over. No-one skates through life without any sex problems and if you can't talk about them, you've got zero chance of solving them.
'The world divides into people who love dressing up and acting out sexual scenarios and those who would rather sit on the tube stark naked'
You should plan sex sessions
Planning is good but it has to be done a certain way or it just becomes another chore added to the list. Simply saying 'We've got to have sex tonight' is about as sexy as 'Tonight we're going to clean out the closet'. But if tonight is the night you're going to try something different like tying each other up, suddenly it is exciting.
Planning something new and naughty is erotic. Adding sex to the 'To Do' list isn't.
You should have sex for 20 minutes or longer
This one came about because of a survey result that said most women take 20 minutes to climax. Everyone took that to mean 20 minutes of general foreplay but in fact, it meant 20 minutes of direct and consistent clitoral stimulation.
People also missed the crucial words 'up to', as in it can take women up to 20 minutes, rather than it always does. Lots of women are able to orgasm in two minutes, others may take 40 minutes if not really in the mood.
Also, setting a minimum time limit on sex often demotivates couples. If you're struggling to find the energy to even kiss your partner because you're juggling two young kids and a job and are utterly exhausted, being told sex isn't worth doing unless you're prepared to devote half an hour, puts lots of couples off doing it at all.
For years, men have been told to act like women in bed - even going so far as to scatter rose petals on the sheets every night
Role-play spices things up
The world divides into people who love dressing up and acting out sexual scenarios and those who would rather sit on the tube stark naked.
As a general rule, people who quite like being the centre of attention and aren't self-conscious, respond perkily to the suggestion of playing cops and robbers or doctors and nurses. Shy, body-conscious, reserved types simply go pale.
Lots of women are able to orgasm in two minutes, others may take 40 minutes if not really in the mood
If you're having great sex, you've got a good relationship
It's a good indicator but not a blanket rule. For instance, you'll often have your most intense sex with people who treat you badly. Sex fuelled by anxiety, vulnerability, high emotion and longing for someone we're worried doesn't want us, is drenched with adrenaline. This sharpens nerve endings and makes everything feel way more concentrated.
Not all good sex is healthy sex. Couples who argue constantly and feel a lot of anger towards each other often have more explosive sex than couples who get on well and have a good relationship.
He can tell if you're faking it
Men got very excited about the news that a red rash appears briefly on our chest or neck during an orgasm. At last, a way to tell who's fibbing and who's not! Trouble is, while most people do get the rash, it's not universal so not absolutely reliable.
A flushed face, the rash, vaginal contractions, a rapid heart rate and a clitoris that's sensitive to touch directly afterward are all clues we've genuinely climaxed.
But if you want a more accurate assessment than that, you'll need to fork out a couple of million for a device that measures activity in the cerebral cortex.
Not all good sex is healthy sex - couples who argue constantly and often have more explosive sex than couples who get on well and have a good relationship
He should have sex like a woman
For years, men have been told to act like women in bed. At one point, they were practically told to start every sex session with a full body massage, preceded by a two hour chat about 'the relationship'. Oh, and rose petals scattered on the sheets were mandatory, even on Monday nights.
Everybody took this advice on board - and the affair rate climbed higher. That worked then. Not.
The reason why it didn't is that danger is what keeps sex red hot long term – this is why couples that are really close friends have problems sustaining desire over time. It's more male-style 'saucy sex' that keeps lust alive, not 'comfort sex'.
Clearly, there are some 'female' sex traits men do need to pay attention to but there's lots about the male approach to sex that women can learn from. Grabbing it when you can. Not expecting every sex session to last for ages. Having dirty sex and saying 'Sod it if the neighbours see or hear'. The male sexual psyche might be morally murkier, but that's not necessarily a bad thing.
To hear more of Tracey Cox's advice, visit her MailOnline sex blog here.
Through her MailOnline blog, the UK's leading sexpert Tracey Cox brings you the latest news as well as offering advice and answering your questions.
Tracey has an academic background in psychology, has written 14 books on sex, relationships and body language and has hosted many TV shows on these topics across her career to date.
Feel free to leave your comments on Tracey's blog and post any question that you would like her to answer, or a topic you would like her to broach.
To ask Tracey something confidentially that she can answer in a forthcoming post, you can contact her via her website at traceycox.com.
Read more: http://www.dailymail.co.uk/femail/article-2282126/He-CANT-tell-youre-faking-FEMAIL-sexpert-Tracey-Cox-busts-common-bedroom-myths.html#ixzz2LYHrpoTB
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