I'm just about to meditate so this is a very short reply. What has helped me is Patikulamanasikara: contemplating on the repulsiveness of the body. Learn about the nine holes of the body and what they eject. Quite simply, learn anatomy. It only needs to be basic. Then, when you find yourself watching women with sensual pleasure, call up your anatomical knowledge of the innards. You already have some of this knowledge. Look at their nostrils. Imagine the mucus, dried snot and nasal hair. When you're looking at their buttocks, think about the primary purpose of the buttocks. They facilitate the flow of faecal matter so imagine diarrhoea dribbling down their legs. Use your imagination and get creative. This type of sensual desire can be a huge hindrance.

nothing wrong with healthy sexual desire. Nothing at all. At times the sex drive is low and then if lights up again. And it goes in cycles just like the Maps

I find it very stupid how Buddhist try to alienate Sex and our very much human existence. Its such a normal human function , and not just human but of many beings sharing this Ecosystem with us.

Sure one could go all into maybe not having kids or maybe just one as there are many people on this Planet but has nothing to do with sex being a bad thing to try and eradicate it.

Of course sex impulses can be unhealthy as well either for oneself or others involved and such could be worked on with a help of a psychologist. 

But if you want a very good teaching on being more mindfull/aware of sexual senstaion then this woman (link to video bellow) is the best bet if you ask me that is. If Im not mistaken she might be coming from the Map of Insight territory. Maybe some of you know more about her.

Get to know the sexual impulses well just like we do in Mahasi Noting, getting to know it to its bare bones by using it as an object of meditation (its your mind perceiving it and its your body to sense it, no one esle can do this for you). Thats how things get clear. Going into thinking about it being something bad and comparing it to all the holes in the body is not the best way to do this in my opinion. I mean my 4 year old boy still enjoys eating his own snot. he relly loves it so much that he now hides from us to enjoy that snack I actually know grownups that still do it. They dont find it disgusting. I mean there are folks that have nothing but delight for feaces and urin so for them focusing on the 9 holes would be just a stronger delight etc ... etc ... etc ...

Here is her vid on how to go about it and its a very human normal way of going about this issue. Integrate your meditation into your sex life just the way you do it into the rest of you life. BTW she also wrote a book on this subject that you can find in the vid describtion I think. Check some other vids of hers if you feel like it. Hope Im not stepping overboard as all this is just my point of view and can be discarded of course.

https://www.youtube.com/watch?v=1N0YQ_tL4qM

If you so choose I would suggest a very simple practice to test and see if it gives any results.

You dont think of the sex impulse as bad and having guilty feels for now you simply get the bodily sensation that trigger the drive and you know that its leading towards what usually happens. Fine. No worries all good.

You postpone it for 10 minutes (not try to stop it unless its hurting some one else of course)  sit down and do some Noting practice Aloud (I assume you are home and have a room to do this you dont need to shout but just speak the labes even if with a whisper). You label anything that you sense; vibration, heat, breathing, desire, imagination, errection, pleasant, guilt, etc etc ... once 10 minutes are over you carry on with the sexual impulse. Fine. Very normal.
Once done you get back to the chair and do another 10 minutes to get to know it before and after. Shed a Light all over it so you are not in dark abou it. It is your mind and your body after all. Thats what we are awakening to first and foremost. If dispassion develops on its own fine if not Im sure you will develop more intimicy with your own body and that to is fine  

Hats down to you for bringing this up as for many folks this is a tough subject to deal with.

I ought to add my own experince as you have opened your slef publicly so will I

I remember when I decided to do my 2nd 3 day solo retreat and because of the sexual desire that arouse strongly during the sitting meditation (whoch resulted in masturbation) I felt so guilty that I packed my stuff and left home. I ruined a fine oportunity to do a 3 day retreat just because I failed to see that aspect as yet another sensation worth of my Investigation. Ok, fine. I will know better next time and sit with it for 10 minutes and then masturbate and do the 10 minutes sit afterwards again. When it comes again I do the same.

Same with urge to stream some adult sites; first 10 minutes of Noting Aloud meditation then stearm the adult site and sit again for 10 minutes.

If you are not familiar with Freestyle Noting Aloud by Kenneth Folk check this vid of his (he has more vids which are more detailed);

https://www.youtube.com/watch?v=1W30oR1UDBI

Sex when engaged in improperly/unskilfully causes hurt, harm & suffering to people. 

Therefore, unskilful sexual thoughts & impluses are given up by developing metta (loving-kindness; wishing well-being for others) and compassion (wishing non-harm and non-suffering for others). 

The Buddhist practises are at these links: 
https://suttacentral.net/mn61/en/horner
https://suttacentral.net/mn19/en/sujato
https://www.accesstoinsight.org/tipitaka/sn/sn35/sn35.127.than.html

Kind regards 

Try to observe how your thinking affects you.

Notice when you have sexual thoughts if you are engaging in them because you like it. At first they may arise inadvertently from the unconscious but do you then pursue them intentionally?

Notice how your thinking effects how you feel. As soon as you notice sexual thoughts arising, think about something else. Notice how that affects your urges. (I am not saying you should do this all the time, just try it as an experiement to see what happens, then decide for yourself what you want to think about.)

Also be aware incorrectly suppressing sexual urges can cause them to come out in other sometimes harmful ways so be aware of that risk. There are numerous reports of sex scandals among religious teachers, Buddhist and other. One cause is trying and failing to suppress sexual urges causing them to come out in uncontrolled ways.

Also in men, more frequent sex correlates with lower risk of prostate cancer.

The precept for sexual activity for the lay person is simply to avoid causing harm through sexual activity. 

In my experience, it took a long time to realize a lot of the shame / suffering / uncomfortable feelings around sexuality were culturally driven and based on incoherent notions of karma. I realized it was really perfectly ok to be horny, be attracted to someone, masturbate, etc...It was simply one more dimension of letting go and it hasn't been completely perfected - probably never will. 

That being said, sexuality is obviously a complex topic and this simple letting go doesn't work for everyone for a myriad of reasons. I also understand this is probably not the the type of answer you were looking for.       

I would second Bardo on Patikulamanasikara. Repulsiveness makes it sound a bit puritanical, think of it more like scientifically investigating the reality of what's in the human body and what happens to it. I was a sex addict and this really helped me.

I watched Youtube videos of human dissecitions, childbirth and various operations like heart transplants, amputations, masectomies and penile implants. There's nothing like seeing a real breast from the inside to lessen your attachment to the external appearance. And seeing a penis cut open lessens your attachment to your own member.

When I was tempted to watch a porn video I watched these kind of videos instead. Eventually I could just summon up the images in my head and use it as an automatic speed brake. I found the same technique of visualizing the reality underneath the skin also very helpful in evaporating the sexual thoughts which tend to arise during normal daily life seeing other people's bodies. Maha Bua's book The Path to Arahantship describes this technique very well as it fits into the path as a whole.

If the sexual urge becomes overwhelming or if I need to ground myself to sleep during strong kundalini then I might masturbate. But I try not to think of any sexual imagery at all and instead just focus purely on the physical sensations. I realize now that when I was watching porn or fantasizing than I was hardly even aware of my own bodily pleasure at all. I found that delaying ejactulation would bring the pleasure to almost unbearable levels and it far exceeded anything I have ever experienced during actual sex. I'm sorry but no one else is going to know your body better than you and obviously when you have a sexual partner then you can't devote yourself exclusively to your own pleasure. Sometimes I would enter into a sort of all over body orgasm (maybe like a woman's orgasm?) and it was similar to kundalini/piti sensations from meditation which left me wondering what is sexual pleasure at all really. The best answer I found was Ken Wilber's essay in the book Kundalni Rising where he says that gential pleasure is actually just a narrowing and forced localization of the divine/all over body bliss which infants experience and can be experienced through meditation.

Finally I wanted to see some corpses rotting and since I don't live near any charnel grounds I used google and stumbled on the world of gore sites. I would issue a very strong warning here - go nowhere near them unless you are willing to expose yourself to some of the very worst things you could possibly imagaine seeing (awful accidents and crimes). I have some reservations about their morality, there is a spectrum and you basically have to apply your own filter about what is moral and what you are willing to subject yourself to. Actually the only one that I would recommend is documentingreality which bans anything pornagraphic, most of the others have pornography as well (albeit of a "repulsive" variety) and other kinds of staged material. That having been said, I did find some very graphic mortuary photos of bodies in various stages of decomosistion. I had initial feelings of revulsion but eventually started to see the beauty in them. This is standard Buddhist practice (the "beautiful corpse") and I can testify that it helped a lot in reducing overall attachment to the body as well as the fear of death.

 

Birth Photography
http://www.boredpanda.com/birth-photography-competition-winners-2020/

@OP

Read Jessica Graham's 'Good Sex: How to Get Off Without Checking Out.'  She is a student of Shinzen & Adyashanti.  Can't recommend her advice enough.