Poor genital hygiene is something nobody wants to bring up with a sexual partner. There's no way it's going to be received well – you'll only make the other person feel judged, ashamed, and physically unappealing.
So let's start with a self-imposed commitment to undertaking penis hygiene. Kiwi, Australian, and British men born after the mid-1970s are probably uncircumcised, yet 26 per cent of them don't wash under their foreskin. That means one-quarter of younger guys out there are at risk of a build-up of smegma: a sebaceous, smelly secretion that is the combination of dead skin cells, urine residue, oil, and moisture.
Cleaning your penis is easy (and don't be fooled by the above, circumcised men still need to do it too). The skin on your genital region isn't terribly different from other skin on your body and washing it with soap and water in the shower is enough. It's most important to do this after you've been sweating. If there's a chance you'll have sex in the proceeding few hours, it's pretty essential to have rolled your foreskin back and wiped away any build-up. This isn't just about being polite: amassing of any residue will hold on to bacteria more easily, meaning STIs are a little easier to contract (though do not use "washing" as a method of STI protection, it's not).
Wash your hands before sex too. This sounds like a given, and shouldn't be a specific task that interrupts sex if you maintain regular handwashing throughout your day. If you don't, just think about the dirt, grime, and germs you have accumulated on your fingers throughout the day. Sharing them with another person's body is unhygienic and rude.
Most women know that you should pee after having sex. Sexual contact pushes bacteria up into the urethra, and urinating afterwards helps to flush this all out and prevent UTIs. This advice applies to men too. Even if you don't feel like it, try to pee in the 15 minutes after sex.
Many different orifices can and will be involved in sex. It's important to know they all contain different types of bacteria and they should not be mixed, particularly because the health of a partner's vagina (if they have one) can be put at risk if doing so. If your penis,
fingers, mouth, or a sex toy penetrate an anus, they need to be washed with soap before penetrating the vagina. Neither is "dirty" on its own, but introducing bacteria from one to the other can lead to infections.
Women are advised not to douche with water or other fluids before sex, because it upsets the natural bacterial balance of the vagina. For men engaging in any kind of anal play, douching is in fact a good idea. Whether you're male or female, all human sex organs are also used to get rid of the body's waste. While some people on a healthy, high-fibre diet don't have any issues in the rear area, others have dietary sensitivities or intolerances and feel more comfortable having washed their rectum out with water before anything goes in there.
All sex toys and other peripherals need to be thoroughly washed after sex too. These inorganic materials that can infect the body if not cleaned and stored properly between uses. Both sexual fluids and blood can lay around on toys, so they should never be shared either. Hot water and soap do the trick (yes, in case you're wondering, you can put a dildo in the dishwasher!) and keep them in a plastic or other protective bag between uses.
The post-sex hygiene stuff is all pretty self-explanatory. Dispose of condoms in the rubbish bin, not down the toilet. Deal with any wet patches either by spot cleaning or washing the sheets. You might like to shower after sex, but you don't have to do it immediately. Neither partner should take this personally (it doesn't mean one of you is unclean) but sex is like exercise: you wouldn't go to the gym without a rinse afterwards.
Lastly, don't forget about regular STI check-ups (at least annually if you're sexually active with one partner, three-monthly for multiple partners). Bring up any issues honestly with your doctor or nurse, and also make sure you're vaccinated against HPV (it can prevent genital warts, penile/anal cancers, and passing the virus on), various types of hepatitis, and other diseases that can be transmitted sexually.